http://www.cnblogs.com/kingangWang/archive/2011/08/15/2139119.html

public static class TreeViewCheck

{

    /// <summary>

    /// 系列节点 Checked 属性控制

    /// </summary>

    /// <param name="e"></param>

    public static void CheckControl(TreeViewEventArgs e)

    {

        if (e.Action != TreeViewAction.Unknown)

        {

            if (e.Node != null && !Convert.IsDBNull(e.Node))

            {

                CheckParentNode(e.Node);

                if (e.Node.Nodes.Count > 0)

                {

                    CheckAllChildNodes(e.Node, e.Node.Checked);

                }

            }

        }

    }

    #region 私有方法

    //改变所有子节点的状态

    private static void CheckAllChildNodes(TreeNode pn, bool IsChecked)

    {

        foreach (TreeNode tn in pn.Nodes)

        {

            tn.Checked = IsChecked;

            if (tn.Nodes.Count > 0)

            {

                CheckAllChildNodes(tn, IsChecked);

            }

        }

    }

    //改变父节点的选中状态，此处为所有子节点不选中时才取消父节点选中，可以根据需要修改

    private static void CheckParentNode(TreeNode curNode)

    {

        bool bChecked = false;

        if (curNode.Parent != null)

        {

            foreach (TreeNode node in curNode.Parent.Nodes)

            {

                if (node.Checked)

                {

                    bChecked = true;

                    break;

                }

            }

            if (bChecked)

            {

                curNode.Parent.Checked = true;

                CheckParentNode(curNode.Parent);

            }

            else

            {

                curNode.Parent.Checked = false;

                CheckParentNode(curNode.Parent);

            }

        }

    }

    #endregion

}

调用方法：在treeview的AfterCheck事件中

private void treeView1_AfterCheck(object sender, TreeViewEventArgs e) 
{ 
    TreeViewCheck.CheckControl(e)

}