Abstract: The power processing unit（PPU）of ion electric propulsion system on the deep space detector needs to adapt to wide range voltage input, wide range voltage output and wide range power output, which results in the increase of component stress, volume and weight and decrease of efficiency of PPU. According to the requirements of grid power supply for ion electric propulsion PPU of small objects detector in China, the input voltage is 60 ~ 110 V, the output voltage is 420 ~ 1 260 V, and the output current is 0.3 ~ 2.1 A. In this paper, the design of grid power supply is studied from the aspects of power module decomposition, soft switching topology selection, single-stage power converter topology design and two-stage power converter topology design. A comprehensive optimization scheme in efficiency, volume and reliability is proposed. The physical verification of the design of single power module of grid power supply is carried out. The results show that the optimized module decomposition and fixed output voltage can effectively reduce the component stress, optimize the efficiency of the converter working point and improve the reliability of the converter; when using the single-stage phase shifted full bridge and full bridge LLC to design wide range input converters, there are still some problems, such as high stress of semiconductor power components, high capacitance stress, and difficult processing of magnetic components; the buck / boost + full bridge LLC two-stage topology scheme can simplify the stress of high-voltage rectifier circuit and adapt to wide range input. It is a preferred scheme for wide range input and output Beam power supply.