The shortage of water resources and pollution has become the major problems affecting people's production and life, and the increasing emissions and low efficiency of sewage treatment the contradiction between the contradiction of water resource in China is becoming more and more obvious. In this situation, how to design a control effect of the sewage treatment system and improve the efficiency of wastewater treatment depending on the current urgently needs to solve the problem. This paper introduces the basic process of sewage treatment and processes. And in view of the present systematic problems in sewage treatment of our country, using advanced control technology, design a wastewater treatment system based on PLC control. So as to realize the automatic control of sewage treatment system. Using this technique for sewage treatment system, not only can enhance the stability of the system, but also can reduce the labor intensity of workers. So as to improve the production efficiency.