Abstract: This paper present the detailed analysis of the principle of chopper power supply of China Spallation Neutron Source (CSNS ) linear accelerator. The rising edge and the falling edge of the chopped beam bunch are important indexes of the performance of the chopper power supply. Based on the research, a chopper power supply with pulse amplitude of 6 kV and nanosecond grade edge is developed. The method of pure hardware circuit instead of software is used to realize the synchronization and AND processing of high frequency and low frequency signals, which can make the power supply output stable and reliable high voltage pulse. The power supply has two modes (multi pulse and single pulse) to meet the requirements of single beam or multi beam injection into the Rapid Cycling Synchrotron(RCS) ring. The results of the CSNS linac beam chop experiment show that the power supply meets all the design requirements.