In this article, a new concept named ‘Closed-loop Manufacturing System’ (CLMS) is introduced. The Workpiece Machining Precision PID Control Model (WMPPCM) is proposed and described. PID error compensation model expressions are structured. The experimental method of WMPPCM is established. In the experiment, WMPPCM could be utilized to estimate the trend of machining error so as to conduct the adjustment before production. The experiment has verified the feasibility and validity of WMPPCM. The experiments have also proved that WMPPCM can decrease machining error more effectively then traditional CNC machining method.