Based on the minimum system of onboard terminal processing equipment, a scheme of on-orbit software reconfiguration system is designed. According to the characteristics of current satellite information flow, the system framework is designed, and the minimum system composition, general function set and the whole satellite security functional requirements of the onboard terminal equipment processor are proposed. In the system, the application software program data is made into data transfer frame and transmitted into the satellite through the telecommand channel, which can be stored in the memory of OBDH subsystem and send to the terminal equipment. Application program can be bootload and managed by the minimum system with error control design to ensure its reliability and safety. The test shows that the system can realize the reliable transfer, storage and bootload of onboard microcomputer software and FPGA configuration data.