在C# WPF中实现PasswordBox的MVVM绑定，‌并确保在焦点离开时才更新数据，‌确实需要一些特殊的处理，‌因为PasswordBox控件本身并不直接支持双向数据绑定。‌本文采用创建 PasswordHelper 附加属性类来实现

public static class PasswordHelper
{
    public static readonly DependencyProperty PasswordProperty =
            DependencyProperty.RegisterAttached(
                "Password",
                typeof(string),
                typeof(PasswordHelper),
                new PropertyMetadata(string.Empty, OnPasswordPropertyChanged)
            );
    public static string GetPassword(DependencyObject PasswordObject)
    {
        return (string)PasswordObject.GetValue(PasswordProperty);
    }

    public static void SetPassword(DependencyObject PasswordObject, string PasswordValue)
    {
        PasswordObject.SetValue(PasswordProperty, PasswordValue);
    }

    private static void OnPasswordPropertyChanged(DependencyObject PasswordObject, DependencyPropertyChangedEventArgs Password)
    {
        PasswordBox PasswordBox = (PasswordBox)PasswordObject;
        PasswordBox.LostFocus -= PasswordChanged;
        PasswordBox.Password = Password.NewValue.ToString();
        PasswordBox.LostFocus += PasswordChanged;
    }
    private static void PasswordChanged(object PasswordObject, RoutedEventArgs _)
    {
        SetPassword((PasswordBox)PasswordObject, ((PasswordBox)PasswordObject).Password);
    }
}

引入命名空间 xmlns:Common=“clr-namespace:命名空间名”

<PasswordBox Common:PasswordHelper.Password="{Binding V.ButtonName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>