Abstract: This paper discusses the design feature of the repetitive Marx generator, and presents the electrostatic field in switch cavity. Based on the theoretic analysis and experimental research, a 12 stage repetitive Marx generator with inductive isolators has been developed recently, it is charged synchronously with positive and negative constant current. Elements of the Marx generator were compactly arranged to attain lower circuit inductance. Experiments show 532 kV output peak voltage with rise-time about 40 ns and the generator’s set-up time is about 32 ns. Filled with pure SF6 gas in switch cavity, the Marx generator works stably in the repetitive frequency of 1~50 Hz.