尝试级联下拉菜单 -

使用ASP.net在Ajax中加载DropDown [ ^ ]

在ASP.Net中创建级联DropDownLists [ ^ ]

CascadingDropDown演示 [ ^ ]

Try out cascading dropdowns -
CascadingDropDown in Ajax With ASP.net[^]
Creating Cascading DropDownLists in ASP.Net[^]
CascadingDropDown Demonstration[^]