To optimize the structure of bladder power pump, a new urethra valve was designed. Based on the theories of electromagnetics and hydromechanics, the mathematic model of urethra valve was built, and the effects on the performance of urethra valve were analyzed, taking into account different influence factors such as electromagnet current, air gap and so on. The validity of the model was confirmed through the comparison between simulation and experiment. On the simulated test bed, the effects of urethra valve on the micturition performance of bladder power pump were studied. The results show that increasing the electromagnet current and decreasing the air gap between electromagnet and urethra valve are beneficial to increase the maximal urine flow rate and decrease the urine flow time. The research provides the basis for the performance analysis and optimal structure design of bladder power pump.