High repetition frequency pulse power source is the future development direction of pulsed power source technology. After discharge of pulse capacitor, there will remain a large amount of electrical energy. Residual energy need to discharge for security reason. In order to realize the pulse power source high repetition frequency discharge technology, residual capacity on the pulse capacitor must be released carry on the rapid. The traditional mechanical switch conduction time is long, opening time is inconsistent. It is not conducive to multimodule pulse power source of the rapid discharge of residual power, so this article uses fast thyristor to replace the traditional mechanical vent switch. The selection of the discharge resistance parameters in practical experiments is given by calculation and analysis .A new hardware circuit for realizing thyristor switch state monitoring function is designed, which compensates the shortcomings of time delay of software detection. The schematic diagram and device parameters of the monitoring circuit are given in combination with practical application. The test results show that this scheme is feasible, Residual energy of the capacitor can be discharged within 0.5 s, which lays the foundation for the realization of high repetition frequency technology.