Abstract: When a pulse power supply is used for sewage treatment, parameters of AC-DC coupling circuit must be repeatedly regulated to make the reactor work in streamer discharge mode, and there are problems of no effective controllable and quantifiable index and imprecise regulation. So the paper proposed a fuzzy control scheme for the reactor which takes streamer discharge coefficient as a controllable and quantifiable parameter to get required superposition signal of AC and DC on the basis of research of voltage amplitude-frequency characteristics of the reactor and the basic condition of streamer discharge. The simulation and experiment results showed the scheme is feasible and effective.