diff --git a/src/components/BootstrapBlazor.Region/Components/SelectCity.razor b/src/components/BootstrapBlazor.Region/Components/SelectCity.razor
index f704ac89..b541d032 100644
--- a/src/components/BootstrapBlazor.Region/Components/SelectCity.razor
+++ b/src/components/BootstrapBlazor.Region/Components/SelectCity.razor
@@ -36,12 +36,12 @@
 
 @code {
     RenderFragment RenderItem(string item) =>
-    @<div class="bb-region-city-item">
+    @<div @key="item" class="bb-region-city-item">
         <div class="bb-region-city-title" @onclick="() => OnSelectProvince(item)">@item</div>
         <ul>
             @foreach (var city in GetCities(item))
             {
-                <li class="@GetActiveClass(city)" @onclick="() => OnSelectCity(city)">@city</li>
+                <li @key="city" class="@GetActiveClass(city)" @onclick="() => OnSelectCity(city)">@city</li>
             }
         </ul>
     </div>;
diff --git a/src/components/BootstrapBlazor.Region/Components/SelectCity.razor.cs b/src/components/BootstrapBlazor.Region/Components/SelectCity.razor.cs
index 2a24fec9..d8918872 100644
--- a/src/components/BootstrapBlazor.Region/Components/SelectCity.razor.cs
+++ b/src/components/BootstrapBlazor.Region/Components/SelectCity.razor.cs
@@ -60,13 +60,20 @@ public partial class SelectCity
     private readonly HashSet<string> _values = [];
     private string? _searchText;
     private bool _showSearch;
+    private IEnumerable<string> _filteredProvinces = Provinces;
+    private HashSet<ProvinceItem>? _provinceItems;
+    private Dictionary<string, HashSet<string>>? _cityPinyin;
 
     private string? GetActiveClass(string item) => CssBuilder.Default()
         .AddClass("active", _values.Contains(item) && IsMultiple)
         .AddClass("active", CurrentValue == item && !IsMultiple)
-        .AddClass("prev", !string.IsNullOrEmpty(_searchText) && StartsWith(PinyinService.GetFirstLetters(item), _searchText))
+        .AddClass("prev", IsPinyinMatch(item))
         .Build();
 
+    private bool IsPinyinMatch(string item) => !string.IsNullOrEmpty(_searchText)
+        && _cityPinyin?.TryGetValue(item, out var pinyin) == true
+        && StartsWith(pinyin, _searchText);
+
     /// <summary>
     /// <inheritdoc/>
     /// </summary>
@@ -84,6 +91,7 @@ protected override void OnParametersSet()
         if (ShowSearch == false)
         {
             _searchText = "";
+            _filteredProvinces = Provinces;
         }
     }
 
@@ -123,7 +131,14 @@ protected override async Task OnAfterRenderAsync(bool firstRender)
     [JSInvokable]
     public void TriggerSearch(string v)
     {
-        _searchText = v.ToUpperInvariant();
+        var searchText = v.ToUpperInvariant();
+        if (_searchText == searchText)
+        {
+            return;
+        }
+
+        _searchText = searchText;
+        _filteredProvinces = FilterProvinces(searchText);
         StateHasChanged();
     }
 
@@ -143,7 +158,7 @@ private async Task OnClearValue()
 
     private RenderFragment RenderCities() => builder =>
     {
-        foreach (var item in GetProvinces())
+        foreach (var item in _filteredProvinces)
         {
             builder.AddContent(0, RenderItem(item));
         }
@@ -190,19 +205,19 @@ private async Task OnSelectCity(string item)
         }
     }
 
-    private HashSet<string> GetProvinces()
+    private IEnumerable<string> FilterProvinces(string searchText)
     {
-        if (string.IsNullOrEmpty(_searchText))
+        if (string.IsNullOrEmpty(searchText))
         {
             return Provinces;
         }
 
-        if (PinyinService.ContainsChinese(_searchText))
+        if (PinyinService.ContainsChinese(searchText))
         {
-            return [.. Provinces.Where(i => i.Contains(_searchText) || GetCities(i).Any(city => city.Contains(_searchText)))];
+            return Provinces.Where(i => i.Contains(searchText) || GetCities(i).Any(city => city.Contains(searchText))).ToArray();
         }
 
-        return [.. GenerateProvincePinYin().Where(i => FilterProvince(i, _searchText)).Select(i => i.Name)];
+        return GenerateProvincePinYin().Where(i => FilterProvince(i, searchText)).Select(i => i.Name).ToArray();
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -211,16 +226,19 @@ private HashSet<string> GetProvinces()
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private static bool StartsWith(HashSet<string> source, string searchText) => source.Any(i => i.StartsWith(searchText, StringComparison.OrdinalIgnoreCase));
 
-    private static HashSet<ProvinceItem>? _provinceItems;
-
     private HashSet<ProvinceItem> GenerateProvincePinYin()
     {
-        _provinceItems ??= [.. Provinces.Select(i => new ProvinceItem()
+        if (_provinceItems is null)
         {
-            PinYin = PinyinService.GetFirstLetters(i),
-            Name = i,
-            Cities = GenerateCityPinYin(i)
-        })];
+            _cityPinyin = [];
+            _provinceItems = [.. Provinces.Select(i => new ProvinceItem()
+            {
+                PinYin = PinyinService.GetFirstLetters(i),
+                Name = i,
+                Cities = GenerateCityPinYin(i)
+            })];
+        }
+
         return _provinceItems;
     }
 
@@ -231,10 +249,15 @@ private HashSet<ProvinceItem> GenerateProvincePinYin()
         _ => RegionService.GetCities(provinceName)
     };
 
-    private HashSet<CityItem> GenerateCityPinYin(string provinceName) => [.. GetCities(provinceName).Select(i => new CityItem()
+    private HashSet<CityItem> GenerateCityPinYin(string provinceName) => [.. GetCities(provinceName).Select(i =>
     {
-        PinYin = PinyinService.GetFirstLetters(i),
-        Name = i
+        var pinyin = PinyinService.GetFirstLetters(i);
+        _cityPinyin![i] = pinyin;
+        return new CityItem()
+        {
+            PinYin = pinyin,
+            Name = i
+        };
     })];
 
     private static readonly HashSet<string> Provinces = [
diff --git a/src/components/BootstrapBlazor.Region/Components/SelectCity.razor.js b/src/components/BootstrapBlazor.Region/Components/SelectCity.razor.js
index 311d51fe..6e460c5f 100644
--- a/src/components/BootstrapBlazor.Region/Components/SelectCity.razor.js
+++ b/src/components/BootstrapBlazor.Region/Components/SelectCity.razor.js
@@ -2,6 +2,7 @@ import Data from "../../BootstrapBlazor/modules/data.js"
 import EventHandler from "../../BootstrapBlazor/modules/event-handler.js"
 import Input from "../../BootstrapBlazor/modules/input.js"
 import Popover from "../../BootstrapBlazor/modules/base-popover.js"
+import { debounce } from "../../BootstrapBlazor/modules/utility.js"
 
 export function init(id, invoke, options) {
     const el = document.getElementById(id);
@@ -37,9 +38,12 @@ const initSearch = region => {
     const { el, invoke, options } = region;
     const searchInput = el.querySelector(".search-text");
     if (searchInput) {
-        Input.composition(searchInput, async v => {
-            await invoke.invokeMethodAsync(options.triggerSearch, v);
-        });
+        const handler = debounce(async v => {
+            if (searchInput.isConnected && searchInput.value === v) {
+                await invoke.invokeMethodAsync(options.triggerSearch, v);
+            }
+        })
+        Input.composition(searchInput, handler);
     }
 
     const search = el.querySelector(".dropdown-menu-search .clear-icon");
diff --git a/test/UnitTestRegion/RegionTest.cs b/test/UnitTestRegion/RegionTest.cs
index f3a86db3..3b295b54 100644
--- a/test/UnitTestRegion/RegionTest.cs
+++ b/test/UnitTestRegion/RegionTest.cs
@@ -2,13 +2,43 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 // Website: https://www.blazor.zone or https://argozhang.github.io/
 
+using Bunit;
+
 namespace UnitTestRegion;
 
-public class RegionTest
+public class RegionTest : IDisposable
 {
+    private readonly Bunit.BunitContext _context = new();
+
+    public RegionTest()
+    {
+        _context.JSInterop.Mode = Bunit.JSRuntimeMode.Loose;
+        _context.Services.AddBootstrapBlazor();
+        _context.Services.AddBootstrapBlazorRegionService();
+    }
+
     [Fact]
-    public void Test1()
+    public async Task Search_Ok()
     {
+        var cut = _context.Render<SelectCity>();
 
+        await cut.InvokeAsync(() => cut.Instance.TriggerSearch("深圳"));
+        var province = Assert.Single(cut.FindAll(".bb-region-city-title"));
+        Assert.Equal("广东省", province.TextContent);
+
+        var pinyinService = _context.Services.GetRequiredService<IPinyinService>();
+        var pinyin = pinyinService.GetFirstLetters("深圳市").MaxBy(i => i.Length)!;
+        await cut.InvokeAsync(() => cut.Instance.TriggerSearch(pinyin));
+        Assert.Contains(cut.FindAll(".bb-region-city-title"), i => i.TextContent == "广东省");
+        Assert.Contains("prev", cut.FindAll("li").Single(i => i.TextContent == "深圳市").ClassList);
+
+        await cut.InvokeAsync(() => cut.Instance.TriggerSearch(""));
+        Assert.Equal(30, cut.FindAll(".bb-region-city-title").Count);
+    }
+
+    public void Dispose()
+    {
+        _context.Dispose();
+        GC.SuppressFinalize(this);
     }
 }
diff --git a/test/UnitTestRegion/UnitTestRegion.csproj b/test/UnitTestRegion/UnitTestRegion.csproj
index ae8644b7..367afdee 100644
--- a/test/UnitTestRegion/UnitTestRegion.csproj
+++ b/test/UnitTestRegion/UnitTestRegion.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <ItemGroup>
+    <PackageReference Include="bunit" Version="2.*" />
     <ProjectReference Include="..\..\src\components\BootstrapBlazor.Region\BootstrapBlazor.Region.csproj" />
   </ItemGroup>