解决方法
请尝试以下方法
//part of the usings using System.Runtime.InteropServices; //declares [DllImport("user32.dll")] private static extern bool PostMessage( IntPtr hWnd,// handle to destination window Int32 msg,// message Int32 wParam,// first message parameter Int32 lParam // second message parameter ); const Int32 WM_LBUTTONDOWN = 0x0201; //method to call dropdown private void button1_Click(object sender,EventArgs e) { Int32 x = dateTimePicker1.Width - 10; Int32 y = dateTimePicker1.Height / 2; Int32 lParam = x + y * 0x00010000; PostMessage(dateTimePicker1.Handle,WM_LBUTTONDOWN,1,lParam); }