diff --git a/src/Ursa.Themes.Semi/Controls/AutoCompleteBox.axaml b/src/Ursa.Themes.Semi/Controls/AutoCompleteBox.axaml
index 5f56b87..facd2d0 100644
--- a/src/Ursa.Themes.Semi/Controls/AutoCompleteBox.axaml
+++ b/src/Ursa.Themes.Semi/Controls/AutoCompleteBox.axaml
@@ -14,11 +14,18 @@
                         Name="PART_TextBox"
                         MinHeight="{TemplateBinding MinHeight}"
                         VerticalAlignment="Stretch"
-                        iri:ClassHelper.ClassSource="{TemplateBinding}"
                         DataValidationErrors.Errors="{TemplateBinding (DataValidationErrors.Errors)}"
                         InnerLeftContent="{TemplateBinding InnerLeftContent}"
                         InnerRightContent="{TemplateBinding InnerRightContent}"
                         Watermark="{TemplateBinding Watermark}" />
+                    <Button
+                        Name="PART_ClearButton"
+                        HorizontalAlignment="Right"
+                        Margin="{DynamicResource TextBoxContentPadding}"
+                        Command="{Binding $parent[u:AutoCompleteBox].Clear}"
+                        Content="{DynamicResource IconButtonClearData}"
+                        IsVisible="False"
+                        Theme="{StaticResource InnerIconButton}" />
                     <Popup
                         Name="PART_Popup"
                         MaxHeight="{TemplateBinding MaxDropDownHeight}"
@@ -45,5 +52,13 @@
                 </Panel>
             </ControlTemplate>
         </Setter>
+        <Style Selector="^.clearButton, ^.ClearButton">
+            <Style Selector="^:focus-within:not(:empty) /template/ Button#PART_ClearButton">
+                <Setter Property="IsVisible" Value="True" />
+            </Style>
+            <Style Selector="^:pointerover:not(:empty) /template/ Button#PART_ClearButton">
+                <Setter Property="IsVisible" Value="True" />
+            </Style>
+        </Style>
     </ControlTheme>
 </ResourceDictionary>
diff --git a/src/Ursa/Controls/AutoCompleteBox/AutoCompleteBox.cs b/src/Ursa/Controls/AutoCompleteBox/AutoCompleteBox.cs
index 17e7d13..115d58f 100644
--- a/src/Ursa/Controls/AutoCompleteBox/AutoCompleteBox.cs
+++ b/src/Ursa/Controls/AutoCompleteBox/AutoCompleteBox.cs
@@ -1,12 +1,22 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
 using Avalonia.Input;
 using Avalonia.Interactivity;
+using Avalonia.VisualTree;
+using Irihi.Avalonia.Shared.Common;
 using Irihi.Avalonia.Shared.Contracts;
 
 namespace Ursa.Controls;
 
 public class AutoCompleteBox : Avalonia.Controls.AutoCompleteBox, IClearControl
 {
+    // ReSharper disable once InconsistentNaming
+    private const string PART_TextBox = "PART_TextBox";
+    private bool _closeBySelectionFlag;
+    
+    private TextBox? _textbox;
     static AutoCompleteBox()
     {
         MinimumPrefixLengthProperty.OverrideDefaultValue<AutoCompleteBox>(0);
@@ -14,18 +24,43 @@ public class AutoCompleteBox : Avalonia.Controls.AutoCompleteBox, IClearControl
 
     public AutoCompleteBox()
     {
-        AddHandler(PointerPressedEvent, OnBoxPointerPressed, RoutingStrategies.Tunnel);
+        AddHandler(PointerReleasedEvent, OnCurrentPointerReleased, RoutingStrategies.Tunnel);
+    }
+
+    private void OnCurrentPointerReleased(object sender, PointerReleasedEventArgs e)
+    {
+        var source = (e.Source as Control).FindAncestorOfType<ListBoxItem>();
+        if (source is not null)
+        {
+            _closeBySelectionFlag = true;
+        }
+    }
+
+    protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
+    {
+        base.OnApplyTemplate(e);
+        _textbox?.RemoveHandler(PointerPressedEvent, OnBoxPointerPressed);
+        _textbox = e.NameScope.Find<TextBox>(PART_TextBox);
+        _textbox?.AddHandler(PointerPressedEvent, OnBoxPointerPressed, handledEventsToo: true);
+        PseudoClasses.Set(PseudoClassName.PC_Empty, string.IsNullOrEmpty(Text));
     }
 
     public void Clear()
     {
-        SetCurrentValue(SelectedItemProperty, null);
+        // Note: this method only resets Text to null. 
+        // By default, AutoCompleteBox will clear the SelectedItem when Text is set to null.
+        // But user can use custom Predicate to control the behavior when Text is set to null.
+        SetCurrentValue(TextProperty, null);
     }
 
     private void OnBoxPointerPressed(object? sender, PointerPressedEventArgs e)
     {
-        if (Equals(sender, this) && e.GetCurrentPoint(this).Properties.IsLeftButtonPressed && IsDropDownOpen == false)
+        if (Equals(sender, _textbox)
+            && e.GetCurrentPoint(this).Properties.IsLeftButtonPressed
+            && IsDropDownOpen == false)
+        {
             SetCurrentValue(IsDropDownOpenProperty, true);
+        }
     }
 
     protected override void OnGotFocus(GotFocusEventArgs e)
@@ -35,6 +70,22 @@ public class AutoCompleteBox : Avalonia.Controls.AutoCompleteBox, IClearControl
         if (e.NavigationMethod == NavigationMethod.Pointer) return;
         if (!this.GetTemplateChildren().Contains(e.Source)) return;
         // If the focus is set by keyboard navigation, open the dropdown.
-        if (IsDropDownOpen == false) SetCurrentValue(IsDropDownOpenProperty, true);
+        if (!_closeBySelectionFlag && IsDropDownOpen == false)
+        {
+            SetCurrentValue(IsDropDownOpenProperty, true);
+        }
+        _closeBySelectionFlag = false;
     }
+
+    protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+    {
+        base.OnPropertyChanged(change);
+        if (change.Property == TextProperty)
+        {
+            var value = change.GetNewValue<string?>();
+            PseudoClasses.Set(PseudoClassName.PC_Empty, string.IsNullOrEmpty(value));
+        }
+    }
+
+    
 }
\ No newline at end of file