private void InitTree2(TreeNodeCollection Nds,string parentId,int flag)
{
DataView dv=new DataView();

TreeNode tmpNd;
dv.Table=dsTree.Tables[0];
dv.RowFilter="ParentId='" + parentId + "'" ;

foreach(DataRowView drv in dv)
{
tmpNd=new TreeNode();

tmpNd.ID = drv["ID"].ToString();
tmpNd.Text = "<INPUT type='checkbox' id='chkPlan' value='"+drv["ID"].ToString()+"' onclick='searchArea(this);'>"+drv["DName"].ToString();

tmpNd.NavigateUrl="DestLocalEdit.aspx?ID="+drv["ID"].ToString()+"&ParentID="+drv["ParentID"].ToString();

Nds.Add(tmpNd);
InitTree2(tmpNd.Nodes,tmpNd.ID,flag);
}
}

如果你希望知道当前选中的是哪些节点，其实可以换个思路，
首先在页面上方一个<INPUT id="Text1" type="hidden" name="Text1" runat="server" value=",">

然后改写一下 searchArea ：
function searchArea(objTreeCheckBox)
{
var curID = objTreeCheckBox.value;
var selected = document.getElementById("Text1").value;
if(objTreeCheckBox.checked)
selected += curID + ",";
else
selected = selected.replace(","+curID+",",",");

document.getElementById("Text1").value = selected;
}

那么，无论是在javascript还是在后台C#代码中都可以随时获取目前选中的节点的value值