diff --git a/App.xaml.cs b/App.xaml.cs
index 5e3e68e..198550f 100644
--- a/App.xaml.cs
+++ b/App.xaml.cs
@@ -301,9 +301,9 @@ namespace DrillTools
         }
 
         /// <summary>
-        /// 从 MainWindowViewModel.Tools 独立遍历计算叠板用最小刀径
-        /// 分类逻辑与 UpdateMinDiameterInfo 一致，但不排除 0.749mm
-        /// 槽刀分类映射：Slot/DustSlot/DeburrSlot → 槽刀，EASlot/EASlot2 → EA刀，Drill → 钻针
+        /// 从 MainWindowViewModel.Tools 独立遍历计算叠板用最小刀径。
+        /// 分类逻辑与 UpdateMinDiameterInfo 一致（按 ToolType 区分圆孔/槽孔），不排除 0.749mm；
+        /// 特殊固定孔径（3.203 等）不参与叠板计算。
         /// </summary>
         private static void CalculateStackMinDiameters(
             ObservableCollection<ToolItem> tools,
@@ -315,26 +315,30 @@ namespace DrillTools
 
             foreach (var tool in tools)
             {
-                // 机台码刀具（ToolType.MachineCode）是固定孔位，不参与叠板计算
                 if (tool.ToolType == ToolType.MachineCode)
                     continue;
 
-                var category = ToolItem.GetToolCategory(tool.ToolSuffixType);
+                if (ToolItem.IsSpecialFixedDiameter(tool.Diameter))
+                    continue;
 
-                switch (category)
+                if (tool.ToolType == ToolType.Regular)
                 {
-                    case ToolCategory.Drill:
-                        if (minDrill == 0 || tool.Diameter < minDrill)
-                            minDrill = tool.Diameter;
-                        break;
-                    case ToolCategory.Slot:
+                    if (minDrill == 0 || tool.Diameter < minDrill)
+                        minDrill = tool.Diameter;
+                }
+                else if (tool.ToolType == ToolType.Slot)
+                {
+                    if (tool.ToolSuffixType != ToolSuffixType.EASlot && tool.ToolSuffixType != ToolSuffixType.EASlot2)
+                    {
                         if (minSlot == 0 || tool.Diameter < minSlot)
                             minSlot = tool.Diameter;
-                        break;
-                    case ToolCategory.EA:
-                        if (minEA == 0 || tool.Diameter < minEA)
-                            minEA = tool.Diameter;
-                        break;
+                    }
+
+                    if ((tool.ToolSuffixType == ToolSuffixType.EASlot || tool.ToolSuffixType == ToolSuffixType.EASlot2)
+                        && (minEA == 0 || tool.Diameter < minEA))
+                    {
+                        minEA = tool.Diameter;
+                    }
                 }
             }
 
diff --git a/StartupSelectionViewModel.cs b/StartupSelectionViewModel.cs
index 63c1ae9..2099ab6 100644
--- a/StartupSelectionViewModel.cs
+++ b/StartupSelectionViewModel.cs
@@ -175,7 +175,7 @@ namespace DrillTools
         public double StackCalcMinDrill { get; set; }
 
         /// <summary>
-        /// 叠板计算用的最小槽刀直径（包含 0.749mm 的槽刀，由调用方独立计算）
+        /// 叠板计算用的最小槽刀直径（仅真实槽孔刀，由调用方独立计算）
         /// </summary>
         public double StackCalcMinSlot { get; set; }
 
diff --git a/ToolItem.cs b/ToolItem.cs
index 3df5ed4..91665af 100644
--- a/ToolItem.cs
+++ b/ToolItem.cs
@@ -218,6 +218,18 @@ namespace DrillTools
             PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
         }
 
+        /// <summary>
+        /// PP定位孔(3.203)、外围参考孔(3.175)、Mark孔(1.049)、机台码(0.499)等特殊孔径。
+        /// 不按尾号归类，且不参与叠板块数计算。
+        /// </summary>
+        public static bool IsSpecialFixedDiameter(double diameter)
+        {
+            return Math.Abs(diameter - 1.049) < 0.001
+                || Math.Abs(diameter - 3.175) < 0.001
+                || Math.Abs(diameter - 3.203) < 0.001
+                || Math.Abs(diameter - 0.499) < 0.001;
+        }
+
         /// <summary>
         /// 根据孔径尾号判断刀具尾号类型
         /// </summary>
@@ -226,9 +238,7 @@ namespace DrillTools
         public static ToolSuffixType GetToolSuffixType(double diameter)
         {
             // 特殊孔径优先判断
-            if (Math.Abs(diameter - 1.049) < 0.001 ||
-                Math.Abs(diameter - 3.175) < 0.001 ||
-                Math.Abs(diameter - 0.499) < 0.001)
+            if (IsSpecialFixedDiameter(diameter))
             {
                 System.Diagnostics.Debug.WriteLine($"[尾号类型判断] 直径={diameter:F3}: 特殊孔径，尾号类型=钻针");
                 return ToolSuffixType.Drill; // 固定为圆孔