diff --git a/src/BootstrapBlazor.WebConsole/Pages/Dropdowns.razor b/src/BootstrapBlazor.WebConsole/Pages/Dropdowns.razor
index 15d92da4faccbdf9d2849928ca79422b1aa402d5..cbec21e5387cbf00de3325c576d0bcbdf5749699 100644
--- a/src/BootstrapBlazor.WebConsole/Pages/Dropdowns.razor
+++ b/src/BootstrapBlazor.WebConsole/Pages/Dropdowns.razor
@@ -61,7 +61,7 @@
     </div>
 </Block>
 
-<Block Title="绑定数据源" Introduction="改变选项时，下拉框内菜单项会增加" CodeFile="dropdown.8.txt">
+<Block Title="绑定数据源" Introduction="改变选项时，下拉框内菜单项会改变" CodeFile="dropdown.8.txt">
     <div class="row">
         <div class="form-group col-12">
             <Radio Items="@RadioItems" OnStateChanged="@OnRadioItemChanged">
diff --git a/src/BootstrapBlazor.WebConsole/Pages/Dropdowns.razor.cs b/src/BootstrapBlazor.WebConsole/Pages/Dropdowns.razor.cs
index 31bb1096a43e21866940c36ac6acc39b38b91b0e..4b2ad6ddcb7e6551a4dc8d1229d0ea0bccffb7ed 100644
--- a/src/BootstrapBlazor.WebConsole/Pages/Dropdowns.razor.cs
+++ b/src/BootstrapBlazor.WebConsole/Pages/Dropdowns.razor.cs
@@ -66,11 +66,34 @@ namespace BootstrapBlazor.WebConsole.Pages
         }
 
         /// <summary>
-        /// 
+        /// 根据Radio改变切换内容
         /// </summary>
         private void OnRadioItemChanged(CheckboxState state, SelectedItem item)
         {
-            RadioDropDownItems.Add(new SelectedItem($"{RadioDropDownItems.Count()}", $"城市 {RadioDropDownItems.Count()}"));
+            var i = 0;
+            switch (item.Text)
+            {
+                case "北京":
+                    RadioDropDownItems = new List<SelectedItem>()
+                    {
+                        new SelectedItem($"{i++}","东城区"),
+                        new SelectedItem($"{i++}","西城区"),
+                        new SelectedItem($"{i++}","朝阳区"),
+                        new SelectedItem($"{i++}","丰台区"),
+                        new SelectedItem($"{i++}",$"{System.DateTime.Now:HH:mm:ss}")
+                    };
+                    break;
+                case "上海":
+                    RadioDropDownItems = new List<SelectedItem>()
+                    {
+                        new SelectedItem($"{i++}","黄浦区"),
+                        new SelectedItem($"{i++}","徐汇区"),
+                        new SelectedItem($"{i++}","长宁区"),
+                        new SelectedItem($"{i++}","静安区"),
+                        new SelectedItem($"{i++}",$"{System.DateTime.Now:HH:mm:ss}")
+                    };
+                    break;
+            }
             StateHasChanged();
         }
 
@@ -165,6 +188,6 @@ namespace BootstrapBlazor.WebConsole.Pages
                 Description="下拉框值发生改变时触发",
                 Type ="EventCallback<SelectedItem>"
             }
-       };
+        };
     }
 }
diff --git a/src/BootstrapBlazor/Components/Dropdown/DropdownBase.cs b/src/BootstrapBlazor/Components/Dropdown/DropdownBase.cs
index f6d0be0724890c2be0a19751781bd395c514080a..6c4995f72ec33651509fa86b4bc92097e81ce925 100644
--- a/src/BootstrapBlazor/Components/Dropdown/DropdownBase.cs
+++ b/src/BootstrapBlazor/Components/Dropdown/DropdownBase.cs
@@ -104,6 +104,7 @@ namespace BootstrapBlazor.Components
             await base.SetParametersAsync(parameters);
 
             if (Color == Color.None) Color = Color.Primary;
+            SelectedItem = Items.FirstOrDefault();
         }
     }
 }