Abstract: Chopper is an important equipment in beam distribution system based on time of heavy ion research facility in Lanzhou(HIRFL). This paper introduces its mode analysis system’s architecture and hardware composition, analyzes corresponding software requirements, and designs the mode analysis program using multithreading technology. Firstly the program reads mode pulse data of chopper from data acquisition card by NI-DAQmx function, then uses the data for further analysis, and finally sends corresponding work mode control instruction to chopper controller through TCP/IP protocol. The designed program meets system requirements, realizing the function of chopper mode automatic conversion, and has passed the field test.