如果我们可以通过覆盖ControlTemplate来实现这一点，那就更好了，但我找不到一种方法。因此，让我建议您创建一个从ComboBox派生的控件。

• • 自定义组合框. cs**

using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
using Microsoft.UI.Xaml.Controls.Primitives;
using Microsoft.UI.Xaml.Media;
using System.Collections.Generic;
using System.Linq;

namespace ComboBoxTest;

public class CustomComboBox : ComboBox
{
    public CustomComboBox() : base()
    {
        this.Loaded += CustomComboBox_Loaded;
    }

    public static IEnumerable<T> FindChildrenOfType<T>(DependencyObject parent) where T : DependencyObject
    {
        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
        {
            DependencyObject child = VisualTreeHelper.GetChild(parent, i);

            if (child is T hit)
            {
                yield return hit;
            }

            foreach (T? grandChild in FindChildrenOfType<T>(child))
            {
                yield return grandChild;
            }
        }
    }

    private void CustomComboBox_Loaded(object sender, RoutedEventArgs e)
    {
        if (FindChildrenOfType<Popup>(this).FirstOrDefault() is Popup popup)
        {
            popup.PlacementTarget = this;
            popup.DesiredPlacement = PopupPlacementMode.RightEdgeAlignedBottom;
        }
    }
}

而且就像平常的ComboBox一样使用它。

• . xaml格式*

<local:CustomComboBox SelectedIndex="0">
    <ComboBoxItem Content="Text1" />
    <ComboBoxItem Content="Text2" />
    <ComboBoxItem Content="Text3" />
</local:CustomComboBox>