Abstract: "Yingguang-1" is a multi-bank program-discharged pulsed power device to investigate the formation, confinement and instability of the high temperature and high density field reversed configuration (FRC) plasma injector for the magnetized target fusion (MTF), which was constructed at the Institute of Fluid Physics (IFP) in 2014. This paper discusses the influence of the crowbar switch on the load current in "Yingguang-1" device by function modeling the crowbar switch with the software Pspice and conducting the preliminary test experiment. The function circuit modeling of the crowbar switch employed in the program-discharged power system, is accurately presented for the first time. The simulation and experiment results show that the crowbar switch can improve the load current's duration effectively and both its closed resistance and inductances can affect the load current's amplitude and duration obviously. As the closing resistance decreases, the current's duration becomes broader, however, the current's amplitude remains the same. As the coupling inductance connecting to the theta pinch main power system decreases, the duration becomes broader. The approximate 4 mΩ closing resistance and 60 nH with 125 nH coupling inductances in the actual crowbar switch have been determined by the simulation based on the measured current. The test results prove that the function modeling of the crowbar switch is correct and it broadens the current duration effectively.