控件 AllowDrop属性改为true，并实现它的DragEnter、DragDrop这两个事件。+++

private void lbFilePath_DragEnter(object sender, DragEventArgs e)
{
if (e.Data.GetDataPresent(DataFormats.FileDrop))
{
e.Effect = DragDropEffects.All;
}
else
{
e.Effect = DragDropEffects.None;
}
}

private void lbFilePath_DragDrop(object sender, DragEventArgs e)
{
string[] s=(string[])e.Data.GetData(DataFormats.FileDrop,false);

for (int i = 0; i < s.Length; i++)
{
lbFilePath.Items.Add(s[i]);
}
}