将您的 TextBox 包裹在 StackPanel 中.如果你通过代码来做，你可以做这样的事情，例如:

Wrap your TextBox in a StackPanel. If you're doing it via code, you could do something like this, for example:

public MainPage()
{
    InitializeComponent();

    var textBox = new TextBox
    {
        AcceptsReturn = true,
        Height = Double.NaN,
        TextWrapping = TextWrapping.Wrap
    };

    var stackPanel = new StackPanel();
    stackPanel.Children.Add(textBox);

    this.LayoutRoot.Children.Add(stackPanel);
}