以下代码实现了当TreeView节点包含CheckBox时保持其父子节点状态一致，即：当选中父节点，子节点会全部自动选上，反之则全部取消。选择某个子节点，同样应该选中这个字节点的父节点（包括祖先节点）。
在网上也找了一些方法，但是我觉得这是TreeView的一个缺陷，因此应该在该控件内部实现，而不应该附加一些外部的js来控制TreeView，有什么问题可以给我留言，我及时更正:

先在后置cs文件里里添加：
protected void Page_Load(object sender, EventArgs e)
 {
      // Load sample data only once, when the page is first loaded.
      if (!IsPostBack)
      {
            SampleTreeView.Attributes.Add("onClick","OnCheckEvent()");
      }
 }
相关js:
 <script language="javascript">
    //checkbox点击事件
    function OnCheckEvent()
    {
        var objNode = event.srcElement;
        if(objNode.tagName != "INPUT" || objNode.type != "checkbox")
            return;
        //获得当前树结点
        var ck_ID = objNode.getAttribute("ID");
        var node_ID = ck_ID.substring(0,ck_ID.indexOf("CheckBox")) + "Nodes";
        var curTreeNode = document.getElementById(node_ID);
        //级联选择
        SetChildCheckBox(curTreeNode,objNode.checked);
        SetParentCheckBox(objNode);
    }
   
    //子结点字符串
    var childIds = "";
    //获取子结点ID数组
    function GetChildIdArray(parentNode)
    {
        if (parentNode == null)
            return;
        var childNodes = parentNode.children;
        var count = childNodes.length;
        for(var i = 0;i < count;i ++)
        {
            var tmpNode = childNodes[i];
            if(tmpNode.tagName == "INPUT" && tmpNode.type == "checkbox")
            {
                childIds = tmpNode.id + ":" + childIds;
            }
            GetChildIdArray(tmpNode);
        }
    }
   
    //设置子结点的checkbox
    function SetChildCheckBox(parentNode,checked)
    {
        if(parentNode == null)
            return;
        var childNodes = parentNode.children;
        var count = childNodes.length;
        for(var i = 0;i < count;i ++)
        {
            var tmpNode = childNodes[i];
            if(tmpNode.tagName == "INPUT" && tmpNode.type == "checkbox")
            {
                tmpNode.checked = checked;
            }
            SetChildCheckBox(tmpNode,checked);
        }
    }
   
    //设置父结点的checkbox
    function SetParentCheckBox(childNode)
    {
        if(childNode == null)
            return;
        var parent = childNode.parentNode;
        if(parent == null || parent == "undefined")
            return;
        do
        {
         parent = parent.parentNode;
        }
        while (parent && parent.tagName != "DIV");
        if(parent == "undefined" || parent == null)
            return;
        var parentId = parent.getAttribute("ID");
        var objParent = document.getElementById(parentId);
        childIds = "";
        GetChildIdArray(objParent);
        //判断子结点状态
        childIds = childIds.substring(0,childIds.length - 1);
        var aryChild = childIds.split(":");
        var result = false;
        //当子结点的checkbox状态有一个为true，其父结点checkbox状态即为true,否则为false
        for(var i in aryChild)
        {
            var childCk = document.getElementById(aryChild[i]);
            if(childCk.checked)
                result = true;
        }
        parentId = parentId.replace("Nodes","CheckBox");
        var parentCk = document.getElementById(parentId);
        if(parentCk == null)
            return;
        if(result)
            parentCk.checked = true;
        else
            parentCk.checked = false;
        SetParentCheckBox(parentCk);
    }
    </script>

以下是treeview的测试脚本：
       <asp:TreeView ShowCheckBoxes=All>  
        <Nodes>
          <asp:TreeNode Value="Home"
           NavigateUrl =""
            Text="Home"
            Target="Content"
            Expanded="True"
            SelectAction=SelectExpand>
            
            <asp:TreeNode Value="1"
              NavigateUrl=""
              Text="Page1"
              Target="Content">
                <asp:TreeNode Value="2"
                              NavigateUrl=""
                              Text="Section 1"
                              Target="Content">
                    <asp:TreeNode Value="3"
                              NavigateUrl=""
                              Text="Section 1"
                              Target="Content"/>
                    <asp:TreeNode Value="4"
                              NavigateUrl=""
                              Text="Section 1"
                              Target="Content"/>
                </asp:TreeNode>
                <asp:TreeNode Value="5"
                              NavigateUrl=""
                              Text="Section 2"
                              Target="Content">
                </asp:TreeNode>
             </asp:TreeNode>
            
              <asp:TreeNode Value="6"
                NavigateUrl=""
                Text="Page 2"
                Target="Content">
                <asp:TreeNode Value="7"
                              NavigateUrl=""
                              Text="Section 1"
                              Target="Content">
                </asp:TreeNode>
                <asp:TreeNode Value="8"
                              NavigateUrl=""
                              Text="Section 2"
                              Target="Content">
                </asp:TreeNode>
              </asp:TreeNode>
          </asp:TreeNode>
        </Nodes>
      </asp:TreeView>
运行在vs2005下正常，脚本不报错