using System.Diagnostics;

string filePath = "文件路径";
string printer = "打印机";
ProcessStartInfo info = new ProcessStartInfo();
info.Arguments = "\"" + printer + "\"";
info.Verb = "PrintTo";
info.FileName = filePath;
info.CreateNoWindow = true;
info.WindowStyle = ProcessWindowStyle.Hidden;
 
Process p = new Process();
p.StartInfo = info;
p.Start();
p.WaitForInputIdle();