The blower is the key equipment in the production process of biochemical aeration in the sewage plant. Preventing the blower from surging is an important foundation and guarantee for the safe and stable production of the system. Taking the control problem of aeration fan in a sewage treatment plant as the research background, the cause of surge and the anti-surge control method are analyzed. Based on SIEMENS S7-300 PLC, the blower anti-surge automatic control system is designed, and good control effects have been achieved in actual production applications.