Abstract: The pulsed power switching circuit is the basic guarantee of a reliable laser power supply. Parameters selection of the switching circuit directly influences the operating condition of thyristors and diodes, which is the basic condition to guarantee the long-term operating reliability of the laser power supply system. Simulation analysis of the switching circuit is carried out in this paper based on PSCAD software, and operating conditions of thyristors and diodes are focused on. This paper points out that the resistance-capacitance circuit parameters, the current-limiting resistance and synchronization performance of triggers have significant impact on the operating condition of thyristors and diodes. It can be determined by the simulation results that excess high current-rising-rate has caused the damage of thyristor gate and large reverse voltage has resulted in the edge breakdown of diode. Finally, an optimization scheme of circuit parameters is put forward.