The invention provides a screen grid power supply control method based on sliding mode control in order to meet the multi-mode and multi-output working requirements of a thruster. A novel hybrid double-H-bridge topology is adopted, a wide-range output voltage can be achieved within a wide input voltage range, soft switching can be achieved, the efficiency can be improved under a high-power operation condition, and heat consumption can be reduced. The phase shift mode adopts sliding-mode control, so that the method can flexibly adapt to the input and output requirements of a power supply, has stronger robustness and meets the operation of the thruster under multiple working conditions and multiple modes, and the problems that the parameters are fixed and unchanged in the whole process and the adaptability is poor after parameter setting calculation of the traditional control are overcome. Moreover, in an actual system, the system state, parameters and the like can be changed, the uncertainty of a power supply system is reflected, and a controller can hardly achieve an optimal control effect.