Paste html from Clipboard 可解决中文乱码问题。

MemoryStream ms = Clipboard.GetData("Html Format") as MemoryStream;
if (ms == null)
{
return;
}

ms.Position = 0;
byte[] vBytes = new byte[ms.Length];
ms.Read(vBytes, 0, (int)ms.Length);

string strFullHtml = Encoding.UTF8.GetString(vBytes); // utf-8