In order to improve the performance of power converters based interconnected system, input and output impedance of power converter are employed to investigate the cause leads to interaction in a typical cascade system, detail theoretical analyse is presented in this paper, then some practical design guide lines are induced to attenuate the interaction among power converters, by applying these rules, the dynamic performance and stability of interconnected system can be improved. Simulation results demonstrate the correctness and effectiveness of the theoretical analysis and the proposed method.