diff --git a/Common/DropdownOptions.cs b/Common/DropdownOptions.cs
index 71e7551..eff1d06 100644
--- a/Common/DropdownOptions.cs
+++ b/Common/DropdownOptions.cs
@@ -26,7 +26,7 @@ namespace CadParamPluging.Common
                 DeliveryStatuses = new List<string> { "毛料态", "车加工" },
                 ProcessMethods = new List<string> { "轧制", "自由锻" },
                 StructuralFeatures = new List<string> { "环形", "方体" },
-                SpecialConditions = new List<string> { "无", "中心冲孔", "非中心冲孔", "有圆头" }
+                SpecialConditions = new List<string> { "无", "中心冲孔", "非中心冲孔", "有圆头", "圆轴" }
             };
         }
 
diff --git a/Common/DropdownOptionsStore.cs b/Common/DropdownOptionsStore.cs
index 6f3b99e..88b7f1c 100644
--- a/Common/DropdownOptionsStore.cs
+++ b/Common/DropdownOptionsStore.cs
@@ -38,6 +38,7 @@ namespace CadParamPluging.Common
 
                     obj.Normalize();
                     EnsureNonEmptyByFallbackToDefault(obj);
+                    EnsureBuiltInOptions(obj);
                     return obj;
                 }
             }
@@ -55,7 +56,15 @@ namespace CadParamPluging.Common
             }
 
             options.Normalize();
-            ValidateNonEmpty(options);
+            var optionsToSave = options.Clone();
+            
+            // 移除内置的选项，不要保存到文件
+            if (optionsToSave.SpecialConditions != null && optionsToSave.SpecialConditions.Contains("圆轴"))
+            {
+                optionsToSave.SpecialConditions.Remove("圆轴");
+            }
+
+            ValidateNonEmpty(optionsToSave);
 
             var path = GetFilePath();
             var dir = Path.GetDirectoryName(path);
@@ -68,7 +77,7 @@ namespace CadParamPluging.Common
             var serializer = new XmlSerializer(typeof(DropdownOptions));
             using (var stream = File.Create(tempPath))
             {
-                serializer.Serialize(stream, options);
+                serializer.Serialize(stream, optionsToSave);
             }
 
             if (File.Exists(path))
@@ -126,5 +135,13 @@ namespace CadParamPluging.Common
                 options.SpecialConditions = defaults.SpecialConditions;
             }
         }
+
+        private static void EnsureBuiltInOptions(DropdownOptions options)
+        {
+            if (options?.SpecialConditions != null && !options.SpecialConditions.Contains("圆轴"))
+            {
+                options.SpecialConditions.Add("圆轴");
+            }
+        }
     }
 }