diff --git a/ConeCalorimeter/Services/ModbusRealtimeDataService.cs b/ConeCalorimeter/Services/ModbusRealtimeDataService.cs
index 1c554a4..e852605 100644
--- a/ConeCalorimeter/Services/ModbusRealtimeDataService.cs
+++ b/ConeCalorimeter/Services/ModbusRealtimeDataService.cs
@@ -18,7 +18,7 @@ public sealed class ModbusRealtimeDataService : IRealtimeDataService
     private const ushort OrificeTemperatureRegister = 30;
     private const ushort SampleTemperatureRegister = 36;
     private const ushort AbsorbanceRegister = 120;
-    private const ushort CFactorRegister = 312;
+    private const ushort CFactorRegister = 308;
     private const ushort HeatReleaseRateRegister = 354;
     private const ushort PeakHeatReleaseRateRegister = 376;
     private const ushort Qa180Register = 366;
diff --git a/ConeCalorimeter/Services/NpoiReportExportService.cs b/ConeCalorimeter/Services/NpoiReportExportService.cs
index a5d223e..dda6102 100644
--- a/ConeCalorimeter/Services/NpoiReportExportService.cs
+++ b/ConeCalorimeter/Services/NpoiReportExportService.cs
@@ -153,6 +153,9 @@ public sealed class NpoiReportExportService : IReportExportService
     {
         ClearSheet(sheet);
 
+        var fourDecimalCellStyle = sheet.Workbook.CreateCellStyle();
+        fourDecimalCellStyle.DataFormat = sheet.Workbook.CreateDataFormat().GetFormat("0.0000");
+
         var headerRow = sheet.CreateRow(0);
         for (var i = 0; i < DataHeaders.Length; i++)
         {
@@ -191,7 +194,7 @@ public sealed class NpoiReportExportService : IReportExportService
             SetNumeric(row, 22, record.CurrentMass);
             SetNumeric(row, 23, record.InitialMass);
             SetNumeric(row, 24, record.PeakHeatReleaseRate);
-            SetNumeric(row, 25, record.CFactor);
+            SetNumeric(row, 25, record.CFactor, fourDecimalCellStyle);
         }
 
         for (var i = 0; i < DataHeaders.Length; i++)
@@ -524,11 +527,16 @@ public sealed class NpoiReportExportService : IReportExportService
         }
     }
 
-    private static void SetNumeric(IRow row, int columnIndex, double value)
+    private static void SetNumeric(IRow row, int columnIndex, double value, ICellStyle? cellStyle = null)
     {
         if (double.IsFinite(value))
         {
-            row.CreateCell(columnIndex).SetCellValue(value);
+            var cell = row.CreateCell(columnIndex);
+            cell.SetCellValue(value);
+            if (cellStyle is not null)
+            {
+                cell.CellStyle = cellStyle;
+            }
         }
     }
 
@@ -601,7 +609,9 @@ public sealed class NpoiReportExportService : IReportExportService
 
     private static string FormatValue(double? value)
     {
-        return value is null || !double.IsFinite(value.Value) ? "" : $"{value.Value:0.00}";
+        return value is null || !double.IsFinite(value.Value)
+            ? ""
+            : value.Value.ToString("0.0000", CultureInfo.InvariantCulture);
     }
 
     private static string FormatSeconds(int? value)
diff --git a/ConeCalorimeter/ViewModels/MainViewModel.cs b/ConeCalorimeter/ViewModels/MainViewModel.cs
index 99f7b35..81a564a 100644
--- a/ConeCalorimeter/ViewModels/MainViewModel.cs
+++ b/ConeCalorimeter/ViewModels/MainViewModel.cs
@@ -25,7 +25,10 @@ public sealed class MainViewModel : ObservableObject
         _deviceStatusText = tcpDeviceConnectionService.StatusText;
         _tcpDeviceConnectionService.ConnectionStatusChanged += DeviceConnectionStatusChanged;
         var testPage = new TestPageViewModel(experimentDataService, tcpDeviceConnectionService);
-        var reportPage = new ReportPageViewModel(experimentDataService, reportExportService);
+        var reportPage = new ReportPageViewModel(
+            experimentDataService,
+            reportExportService,
+            tcpDeviceConnectionService);
         NavigationItems = [];
 
         var testItem = new NavigationItemViewModel("测试界面", testPage);
diff --git a/ConeCalorimeter/ViewModels/ReportFieldViewModel.cs b/ConeCalorimeter/ViewModels/ReportFieldViewModel.cs
index 8c4c86b..3560152 100644
--- a/ConeCalorimeter/ViewModels/ReportFieldViewModel.cs
+++ b/ConeCalorimeter/ViewModels/ReportFieldViewModel.cs
@@ -31,14 +31,14 @@ public sealed class ReportFieldViewModel : ObservableObject
         }
     }
 
-    public void SetAutoValue(string value)
+    public void SetAutoValue(string value, bool overwriteManual = false)
     {
         if (string.IsNullOrWhiteSpace(value))
         {
             return;
         }
 
-        if (!string.IsNullOrWhiteSpace(Value) && !_isAutoFilled)
+        if (!overwriteManual && !string.IsNullOrWhiteSpace(Value) && !_isAutoFilled)
         {
             return;
         }
diff --git a/ConeCalorimeter/ViewModels/ReportPageViewModel.cs b/ConeCalorimeter/ViewModels/ReportPageViewModel.cs
index 4e34eb7..7a4793e 100644
--- a/ConeCalorimeter/ViewModels/ReportPageViewModel.cs
+++ b/ConeCalorimeter/ViewModels/ReportPageViewModel.cs
@@ -14,16 +14,26 @@ namespace ConeCalorimeter.ViewModels;
 
 public sealed class ReportPageViewModel : PageViewModel
 {
+    private const ushort CFactorRegister = 308;
+    private const double CFactorMinimum = 0;
+    private const double CFactorMaximum = 1000;
+    private const double DisplayZeroTolerance = 0.00005;
+    private const string FourDecimalDisplayFormat = "0.0000";
+
     private readonly IExperimentDataService _experimentDataService;
     private readonly IReportExportService _reportExportService;
+    private readonly ITcpDeviceConnectionService _tcpDeviceConnectionService;
+    private ModbusFloatByteOrder? _cFactorByteOrder;
     private string _statusText = "报表信息可手动录入，导出时会合并当前采集数据。";
 
     public ReportPageViewModel(
         IExperimentDataService experimentDataService,
-        IReportExportService reportExportService) : base("报表")
+        IReportExportService reportExportService,
+        ITcpDeviceConnectionService tcpDeviceConnectionService) : base("报表")
     {
         _experimentDataService = experimentDataService;
         _reportExportService = reportExportService;
+        _tcpDeviceConnectionService = tcpDeviceConnectionService;
 
         Sections = CreateSections();
         SummaryItems =
@@ -160,6 +170,7 @@ public sealed class ReportPageViewModel : PageViewModel
             return;
         }
 
+        RefreshCurrentCValueReportField(overwriteManual: true);
         var input = BuildInput();
         var defaultName = BuildDefaultFileName(input);
         var dialog = new SaveFileDialog
@@ -255,6 +266,48 @@ public sealed class ReportPageViewModel : PageViewModel
         FindField("EndTime")?.SetAutoValue(FormatSeconds(LastNonNegative(records, record => record.TestSeconds)));
     }
 
+    private void RefreshCurrentCValueReportField(bool overwriteManual)
+    {
+        if (TryReadCurrentCValueText(out var value))
+        {
+            FindField("CFactor")?.SetAutoValue(value, overwriteManual);
+        }
+    }
+
+    private bool TryReadCurrentCValueText(out string value)
+    {
+        value = string.Empty;
+        if (!_tcpDeviceConnectionService.TryReadFloatValues(CFactorRegister, out var result))
+        {
+            Log.Warning(
+                "Report C factor D{RegisterAddress} read failed before export. ConnectionStatus={ConnectionStatus}.",
+                CFactorRegister,
+                _tcpDeviceConnectionService.StatusText);
+            return false;
+        }
+
+        if (!ModbusFloatSelector.TrySelectRangedFloat(
+                result,
+                CFactorMinimum,
+                CFactorMaximum,
+                out var byteOrder,
+                out var cFactor,
+                out var matchCount,
+                _cFactorByteOrder))
+        {
+            Log.Warning(
+                "Report C factor D{RegisterAddress} has no valid decoded value. Raw={RawHex}, Matches={MatchCount}.",
+                CFactorRegister,
+                result.RawHex,
+                matchCount);
+            return false;
+        }
+
+        _cFactorByteOrder = byteOrder;
+        value = FormatValue(NormalizeDisplayValue(cFactor));
+        return true;
+    }
+
     private ReportFieldViewModel? FindField(string key)
     {
         return Sections.SelectMany(section => section.Fields)
@@ -296,7 +349,14 @@ public sealed class ReportPageViewModel : PageViewModel
 
     private static string FormatValue(double value)
     {
-        return double.IsFinite(value) ? $"{value:0.00}" : string.Empty;
+        return double.IsFinite(value)
+            ? value.ToString(FourDecimalDisplayFormat, CultureInfo.InvariantCulture)
+            : string.Empty;
+    }
+
+    private static double NormalizeDisplayValue(double value)
+    {
+        return Math.Abs(value) < DisplayZeroTolerance ? 0 : value;
     }
 
     private static bool IsValidExperimentRecord(RealtimeDataRecord record)