Abstract: For problem that fuzzy control parameters of complex distribution static synchronous compensator is difficult to adjust, mathematical model of distribution static synchronous compensator based on direct current control and simplify FBD detection method was built, and an optimal design method of fuzzy control parameters based on chaos particle swarm algorithm was proposed on the basis of analysis of traditional fuzzy PI control principle. Results of simulation and experiment show that the optimization method can control DC voltage precisely and enhance noise immunity, meanwhile make the compensating current track the compensation current command value quickly and accurately, which improve the control effect significantly.