Abstract: Through analyzing the data of real Distributed Control System (DCS) intercepted with Sniffer, data protocol of the Symphony system is cracked. The technology of Socket is used to develop the virtual server in the environment of Visual C++ 6.0 by combining with communication characteristics of the system itself. The software is divorced form the hardwares which includes real DPU, data acquisition and data operation devices. The software completes data computing, information transmission and other functions during the engineering station, operator station, virtual Distributed Processing Unit(DPU)and model server. The accuracy and real time of virtual DCS are guaranteed.