Abstract: The rule of charge time of high-voltage circuit in the electronic safety and arming system(ESA) of fuzes is studied. Adopting discrete time-domain method to set up the mathematical model of high-voltage conversion circuit, and analyzing the influence of frequency, duty cycle, primary inductance, different turns ratio parameters how to affect high-voltage convertion circuit charging time. Simulation and experiment results express the mathematical model can reflect the variational trend of actual circuit, and the shortest charge time is 75ms when the frequency of dynamic signal is 100kHz and the duty cycle 0.55.