<script language="javascript">
        function postBackByObject()
        { debugger;
            var element = window.event.srcElement;
        
            if (element.tagName == "INPUT" && element.type == "checkbox")
            {                         
                var checkedState = element.checked;
                while (element.tagName != "TABLE")
                element = element.parentElement;
               
                //unfold the sub nodes
                var aaa = element.rows[0].cells.length - 2;            
                element.rows[0].cells[aaa].childNodes[0].click();
//                var treeviewLine = element.rows[0].cells[aaa].childNodes[0];
//                  
//                var nod = element.nextSibling;
//              
//                if (nod.tagName == "DIV")
//                {
//                    var length  = treeviewLine.id.substring(10,treeviewLine.id.length);
//                    TreeView_ToggleNode(TreeView1_Data,length,treeviewLine,' ',nod);
//                 }
               
                //check the parent nodes
                element = element.parentElement;            
                element = element.previousSibling;

                if (checkedState)
                {
                    if (element !=null)
                    {
                          if (element.tagName == "TABLE")
                          {                            
                                var checkboxIndex = element.rows[0].cells.length - 1;
                                var cell = element.rows[0].cells[checkboxIndex];
                                var checkboxes = cell.getElementsByTagName("INPUT");
                                if (checkboxes.length == 1)
                                    checkboxes[0].checked = checkedState;
                            }
                    }
                }
                if (element == null)
                return; 
            }
        }

后台： this.TreeView1.Attributes.Add("onclick", "postBackByObject()");