In response to the strong coupling of the high voltage circuit in flyback converter of electronic security system, which requires optimization of a large number of parameters during design, this paper proposes a parameter design method for the high voltage circuit. After verifying the accuracy of the circuit model, simulation analysis was conducted by changing the input resistance, PWM signal duty cycle, switching frequency, and output doubling stage at the input voltage of 24 V, transformer turn ratio of 1:67, and load resistance of 6 MΩ. This method combines the working principle and theoretical formula of the flyback converter with the voltage and current curves of the transformer in the simulation results to analyze the impact of changes in parameters on the capacitor boost rate. The simulation results show that the capacitor boost rate is optimal when the input resistance is 1 Ω, the duty cycle is 0.4, and the switching frequency is 40 kHz. The physical circuit and simulation circuit have the same parameters, and the experimental results show that the circuit can output a voltage of 1200 V, which is basically consistent with the simulation results. This method can provide assistance for the design of the high voltage circuit in flyback converter, and significantly shorten the design period.