Abstract: Taking the example of crystal control system, the article introduces a new DCS based on IPC and PLC. For adopting the operating computer and controlling computer independence running, the mode of information serial communication, the technique of permitting mistake is inducted to the software, the control system’s MTTF is prolonged consumedly. By using the OO technology and multithreading technology, the maintenance & upgrade is very easy and convenient. Half year’s running show: this system improves the control precision and the product of crystal, ease the employee’s work intensity, and advance the management.Key words: Machine of Crystal Synthesizing; Control System; Combination of IPC & PLC; serial communication