foreach (Form f in this.MdiChildren)
   f.Close()

现在，如果您想关闭特定窗口，可以尝试类似
的东西

now if u want to close Specific window u can try somthing like

foreach (Form f in this.MdiChildren)
{
     if(f.Name =="Some text")
        f.close();
}

希望 WPF的多窗口界面 CP的[ ^ ]可能会对您有所帮助.

Hope Multiple Window Interface for WPF[^]article from CP might help you.