diff --git a/PetWash.Api/Controllers/OrdersController.cs b/PetWash.Api/Controllers/OrdersController.cs
new file mode 100644
index 0000000..e8ce945
--- /dev/null
+++ b/PetWash.Api/Controllers/OrdersController.cs
@@ -0,0 +1,64 @@
+using Microsoft.AspNetCore.Mvc;
+using PetWash.Api.Models;
+using PetWash.Api.Services;
+
+namespace PetWash.Api.Controllers;
+
+[ApiController]
+[Route("api/[controller]")]
+public class OrdersController : ControllerBase
+{
+    private readonly OrderService _orderService;
+
+    public OrdersController(OrderService orderService)
+    {
+        _orderService = orderService;
+    }
+
+    [HttpPost]
+    public async Task<IActionResult> CreateOrder([FromBody] CreateOrderRequest request)
+    {
+        try
+        {
+            var order = await _orderService.CreateOrderAsync(request.PackageId);
+            return Ok(order);
+        }
+        catch (ArgumentException ex)
+        {
+            return BadRequest(ex.Message);
+        }
+    }
+
+    [HttpPost("{id}/payment")]
+    public async Task<IActionResult> ConfirmPayment(int id)
+    {
+        var order = await _orderService.ConfirmPaymentAsync(id);
+        if (order == null)
+            return NotFound();
+
+        return Ok(order);
+    }
+
+    [HttpGet("{id}")]
+    public async Task<IActionResult> GetOrder(int id)
+    {
+        var order = await _orderService.GetOrderAsync(id);
+        if (order == null)
+            return NotFound();
+
+        return Ok(order);
+    }
+
+    [HttpPut("{id}/status")]
+    public async Task<IActionResult> UpdateStatus(int id, [FromBody] UpdateStatusRequest request)
+    {
+        var order = await _orderService.UpdateOrderStatusAsync(id, request.Status);
+        if (order == null)
+            return NotFound();
+
+        return Ok(order);
+    }
+}
+
+public record CreateOrderRequest(int PackageId);
+public record UpdateStatusRequest(OrderStatus Status);
diff --git a/PetWash.Api/Controllers/PackagesController.cs b/PetWash.Api/Controllers/PackagesController.cs
new file mode 100644
index 0000000..a5236e5
--- /dev/null
+++ b/PetWash.Api/Controllers/PackagesController.cs
@@ -0,0 +1,34 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+using PetWash.Api.Data;
+
+namespace PetWash.Api.Controllers;
+
+[ApiController]
+[Route("api/[controller]")]
+public class PackagesController : ControllerBase
+{
+    private readonly PetWashDbContext _context;
+
+    public PackagesController(PetWashDbContext context)
+    {
+        _context = context;
+    }
+
+    [HttpGet]
+    public async Task<IActionResult> GetPackages()
+    {
+        var packages = await _context.Packages.ToListAsync();
+        return Ok(packages);
+    }
+
+    [HttpGet("{id}")]
+    public async Task<IActionResult> GetPackage(int id)
+    {
+        var package = await _context.Packages.FindAsync(id);
+        if (package == null)
+            return NotFound();
+
+        return Ok(package);
+    }
+}
diff --git a/PetWash.Api/Data/PetWashDbContext.cs b/PetWash.Api/Data/PetWashDbContext.cs
new file mode 100644
index 0000000..a716393
--- /dev/null
+++ b/PetWash.Api/Data/PetWashDbContext.cs
@@ -0,0 +1,24 @@
+using Microsoft.EntityFrameworkCore;
+using PetWash.Api.Models;
+
+namespace PetWash.Api.Data;
+
+public class PetWashDbContext : DbContext
+{
+    public PetWashDbContext(DbContextOptions<PetWashDbContext> options) : base(options) { }
+
+    public DbSet<Package> Packages { get; set; }
+    public DbSet<Order> Orders { get; set; }
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        base.OnModelCreating(modelBuilder);
+
+        // 初始化套餐数据
+        modelBuilder.Entity<Package>().HasData(
+            new Package { Id = 1, Name = "基础清洗", Price = 50, DurationMinutes = 15, Description = "基础清洗服务，适合小型宠物" },
+            new Package { Id = 2, Name = "标准清洗", Price = 80, DurationMinutes = 25, Description = "标准清洗+烘干，适合中型宠物" },
+            new Package { Id = 3, Name = "豪华清洗", Price = 120, DurationMinutes = 35, Description = "深度清洗+烘干+护理，适合大型宠物" }
+        );
+    }
+}
diff --git a/PetWash.Api/Models/DeviceStatus.cs b/PetWash.Api/Models/DeviceStatus.cs
new file mode 100644
index 0000000..efee2f0
--- /dev/null
+++ b/PetWash.Api/Models/DeviceStatus.cs
@@ -0,0 +1,10 @@
+namespace PetWash.Api.Models;
+
+public class DeviceStatus
+{
+    public string Status { get; set; } = "Idle";
+    public bool DoorOpen { get; set; }
+    public bool IsWashing { get; set; }
+    public int? CurrentOrderId { get; set; }
+    public DateTime LastUpdated { get; set; }
+}
diff --git a/PetWash.Api/Models/Order.cs b/PetWash.Api/Models/Order.cs
new file mode 100644
index 0000000..5f35df1
--- /dev/null
+++ b/PetWash.Api/Models/Order.cs
@@ -0,0 +1,26 @@
+namespace PetWash.Api.Models;
+
+public class Order
+{
+    public int Id { get; set; }
+    public int PackageId { get; set; }
+    public Package? Package { get; set; }
+    public DateTime CreatedAt { get; set; }
+    public OrderStatus Status { get; set; }
+    public bool IsPaid { get; set; }
+    public DateTime? PaidAt { get; set; }
+    public DateTime? StartedAt { get; set; }
+    public DateTime? CompletedAt { get; set; }
+}
+
+public enum OrderStatus
+{
+    Created,
+    WaitingPayment,
+    Paid,
+    DoorOpened,
+    DoorClosed,
+    Washing,
+    Completed,
+    Cancelled
+}
diff --git a/PetWash.Api/Models/Package.cs b/PetWash.Api/Models/Package.cs
new file mode 100644
index 0000000..ee6534f
--- /dev/null
+++ b/PetWash.Api/Models/Package.cs
@@ -0,0 +1,10 @@
+namespace PetWash.Api.Models;
+
+public class Package
+{
+    public int Id { get; set; }
+    public string Name { get; set; } = string.Empty;
+    public decimal Price { get; set; }
+    public int DurationMinutes { get; set; }
+    public string Description { get; set; } = string.Empty;
+}
diff --git a/PetWash.Api/PetWash.Api.csproj b/PetWash.Api/PetWash.Api.csproj
new file mode 100644
index 0000000..91404dd
--- /dev/null
+++ b/PetWash.Api/PetWash.Api.csproj
@@ -0,0 +1,19 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Swashbuckle.AspNetCore" Version="6.6.2" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="8.0.0" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="8.0.0">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="MQTTnet.AspNetCore" Version="4.3.7.1207" />
+  </ItemGroup>
+
+</Project>
diff --git a/PetWash.Api/PetWash.Api.http b/PetWash.Api/PetWash.Api.http
new file mode 100644
index 0000000..50bf7f1
--- /dev/null
+++ b/PetWash.Api/PetWash.Api.http
@@ -0,0 +1,6 @@
+@PetWash.Api_HostAddress = http://localhost:5274
+
+GET {{PetWash.Api_HostAddress}}/weatherforecast/
+Accept: application/json
+
+###
diff --git a/PetWash.Api/Program.cs b/PetWash.Api/Program.cs
new file mode 100644
index 0000000..0d9aeff
--- /dev/null
+++ b/PetWash.Api/Program.cs
@@ -0,0 +1,51 @@
+using Microsoft.EntityFrameworkCore;
+using PetWash.Api.Data;
+using PetWash.Api.Services;
+
+var builder = WebApplication.CreateBuilder(args);
+
+// 添加数据库
+builder.Services.AddDbContext<PetWashDbContext>(options =>
+    options.UseSqlite(builder.Configuration.GetConnectionString("DefaultConnection") ?? "Data Source=petwash.db"));
+
+// 添加服务
+builder.Services.AddSingleton<MqttService>();
+builder.Services.AddHostedService(provider => provider.GetRequiredService<MqttService>());
+builder.Services.AddScoped<OrderService>();
+
+// 添加CORS
+builder.Services.AddCors(options =>
+{
+    options.AddDefaultPolicy(policy =>
+    {
+        policy.AllowAnyOrigin()
+              .AllowAnyMethod()
+              .AllowAnyHeader();
+    });
+});
+
+builder.Services.AddControllers();
+builder.Services.AddEndpointsApiExplorer();
+builder.Services.AddSwaggerGen();
+
+var app = builder.Build();
+
+// 初始化数据库
+using (var scope = app.Services.CreateScope())
+{
+    var db = scope.ServiceProvider.GetRequiredService<PetWashDbContext>();
+    db.Database.EnsureCreated();
+}
+
+if (app.Environment.IsDevelopment())
+{
+    app.UseSwagger();
+    app.UseSwaggerUI();
+}
+
+app.UseCors();
+app.UseHttpsRedirection();
+app.UseAuthorization();
+app.MapControllers();
+
+app.Run();
diff --git a/PetWash.Api/Properties/launchSettings.json b/PetWash.Api/Properties/launchSettings.json
new file mode 100644
index 0000000..f2c4d0c
--- /dev/null
+++ b/PetWash.Api/Properties/launchSettings.json
@@ -0,0 +1,41 @@
+{
+  "$schema": "http://json.schemastore.org/launchsettings.json",
+  "iisSettings": {
+    "windowsAuthentication": false,
+    "anonymousAuthentication": true,
+    "iisExpress": {
+      "applicationUrl": "http://localhost:58807",
+      "sslPort": 44392
+    }
+  },
+  "profiles": {
+    "http": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "launchUrl": "swagger",
+      "applicationUrl": "http://localhost:5274",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "https": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "launchUrl": "swagger",
+      "applicationUrl": "https://localhost:7203;http://localhost:5274",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "IIS Express": {
+      "commandName": "IISExpress",
+      "launchBrowser": true,
+      "launchUrl": "swagger",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}
diff --git a/PetWash.Api/Services/MqttService.cs b/PetWash.Api/Services/MqttService.cs
new file mode 100644
index 0000000..1d0fe54
--- /dev/null
+++ b/PetWash.Api/Services/MqttService.cs
@@ -0,0 +1,68 @@
+using MQTTnet;
+using MQTTnet.Server;
+using System.Text;
+using System.Text.Json;
+
+namespace PetWash.Api.Services;
+
+public class MqttService : IHostedService
+{
+    private readonly MqttServer _mqttServer;
+    private readonly ILogger<MqttService> _logger;
+
+    public MqttService(ILogger<MqttService> logger)
+    {
+        _logger = logger;
+        
+        var optionsBuilder = new MqttServerOptionsBuilder()
+            .WithDefaultEndpoint()
+            .WithDefaultEndpointPort(1883);
+
+        _mqttServer = new MqttFactory().CreateMqttServer(optionsBuilder.Build());
+        
+        _mqttServer.ClientConnectedAsync += OnClientConnected;
+        _mqttServer.ClientDisconnectedAsync += OnClientDisconnected;
+    }
+
+    public async Task StartAsync(CancellationToken cancellationToken)
+    {
+        await _mqttServer.StartAsync();
+        _logger.LogInformation("MQTT Broker started on port 1883");
+    }
+
+    public async Task StopAsync(CancellationToken cancellationToken)
+    {
+        await _mqttServer.StopAsync();
+        _logger.LogInformation("MQTT Broker stopped");
+    }
+
+    private Task OnClientConnected(ClientConnectedEventArgs args)
+    {
+        _logger.LogInformation($"Client connected: {args.ClientId}");
+        return Task.CompletedTask;
+    }
+
+    private Task OnClientDisconnected(ClientDisconnectedEventArgs args)
+    {
+        _logger.LogInformation($"Client disconnected: {args.ClientId}");
+        return Task.CompletedTask;
+    }
+
+    public async Task PublishAsync(string topic, object payload)
+    {
+        var json = JsonSerializer.Serialize(payload);
+        var message = new MqttApplicationMessageBuilder()
+            .WithTopic(topic)
+            .WithPayload(json)
+            .WithQualityOfServiceLevel(MQTTnet.Protocol.MqttQualityOfServiceLevel.AtLeastOnce)
+            .WithRetainFlag(false)
+            .Build();
+
+        await _mqttServer.InjectApplicationMessage(new InjectedMqttApplicationMessage(message)
+        {
+            SenderClientId = "PetWash.Api"
+        });
+
+        _logger.LogInformation($"Published to {topic}: {json}");
+    }
+}
diff --git a/PetWash.Api/Services/OrderService.cs b/PetWash.Api/Services/OrderService.cs
new file mode 100644
index 0000000..4bd9f9a
--- /dev/null
+++ b/PetWash.Api/Services/OrderService.cs
@@ -0,0 +1,96 @@
+using Microsoft.EntityFrameworkCore;
+using PetWash.Api.Data;
+using PetWash.Api.Models;
+
+namespace PetWash.Api.Services;
+
+public class OrderService
+{
+    private readonly PetWashDbContext _context;
+    private readonly MqttService _mqttService;
+    private readonly ILogger<OrderService> _logger;
+
+    public OrderService(PetWashDbContext context, MqttService mqttService, ILogger<OrderService> logger)
+    {
+        _context = context;
+        _mqttService = mqttService;
+        _logger = logger;
+    }
+
+    public async Task<Order> CreateOrderAsync(int packageId)
+    {
+        var package = await _context.Packages.FindAsync(packageId);
+        if (package == null)
+            throw new ArgumentException("套餐不存在");
+
+        var order = new Order
+        {
+            PackageId = packageId,
+            CreatedAt = DateTime.Now,
+            Status = OrderStatus.WaitingPayment,
+            IsPaid = false
+        };
+
+        _context.Orders.Add(order);
+        await _context.SaveChangesAsync();
+
+        _logger.LogInformation($"订单创建成功: OrderId={order.Id}, PackageId={packageId}");
+        return order;
+    }
+
+    public async Task<Order?> ConfirmPaymentAsync(int orderId)
+    {
+        var order = await _context.Orders.Include(o => o.Package).FirstOrDefaultAsync(o => o.Id == orderId);
+        if (order == null) return null;
+
+        order.IsPaid = true;
+        order.PaidAt = DateTime.Now;
+        order.Status = OrderStatus.Paid;
+        await _context.SaveChangesAsync();
+
+        // 支付成功后，通过MQTT发送开门指令
+        await _mqttService.PublishAsync("device/command", new
+        {
+            command = "open_door",
+            orderId = order.Id,
+            timestamp = DateTime.Now
+        });
+
+        _logger.LogInformation($"订单支付成功，已发送开门指令: OrderId={orderId}");
+        return order;
+    }
+
+    public async Task<Order?> UpdateOrderStatusAsync(int orderId, OrderStatus status)
+    {
+        var order = await _context.Orders.FindAsync(orderId);
+        if (order == null) return null;
+
+        order.Status = status;
+
+        if (status == OrderStatus.DoorClosed)
+        {
+            order.StartedAt = DateTime.Now;
+            // 门关闭后，发送开始清洗指令
+            await _mqttService.PublishAsync("device/command", new
+            {
+                command = "start_wash",
+                orderId = order.Id,
+                durationMinutes = order.Package?.DurationMinutes ?? 15,
+                timestamp = DateTime.Now
+            });
+        }
+        else if (status == OrderStatus.Completed)
+        {
+            order.CompletedAt = DateTime.Now;
+        }
+
+        await _context.SaveChangesAsync();
+        _logger.LogInformation($"订单状态更新: OrderId={orderId}, Status={status}");
+        return order;
+    }
+
+    public async Task<Order?> GetOrderAsync(int orderId)
+    {
+        return await _context.Orders.Include(o => o.Package).FirstOrDefaultAsync(o => o.Id == orderId);
+    }
+}
diff --git a/PetWash.Api/appsettings.Development.json b/PetWash.Api/appsettings.Development.json
new file mode 100644
index 0000000..0c208ae
--- /dev/null
+++ b/PetWash.Api/appsettings.Development.json
@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}
diff --git a/PetWash.Api/appsettings.json b/PetWash.Api/appsettings.json
new file mode 100644
index 0000000..d5a869d
--- /dev/null
+++ b/PetWash.Api/appsettings.json
@@ -0,0 +1,12 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*",
+  "ConnectionStrings": {
+    "DefaultConnection": "Data Source=petwash.db"
+  }
+}