InitializeComponent()将实例化标记，包括绑定.此时， DTUsers 仍然为 null ，因此什么也不显示.然后，您更改 DTUsers ，但是绑定(因此网格)无法知道您已完成操作-因此它不会执行任何操作.

InitializeComponent() will instantiate your markup, including the binding. At that point DTUsers is still null, so nothing is displayed. Then, you change DTUsers, but there's no way for the binding (and therefore the grid) to know that you did it - and so it does not do anything.

您应该将 DTUsers 设置为依赖项属性，或者在您的类上实现 INotifyPropertyChanged ，并在更改的值后引发 PropertyChanged 事件财产.

You should either make DTUsers a dependency property, or implement INotifyPropertyChanged on your class, and raise PropertyChanged event after you change the value of the property.