Abstract: High reliability and system updating ability of data processing system are required for long-life medium high orbit satellite. a high reliability data processing system based on Godson is proposed. The system takes "Godson + double NorFlash" as the hardware architecture, designs the software reconstruction scheme on orbit, and adopts the cross backup design of sub boards based on dual redundant bus. The system software can be reconstructed and upgraded on orbit, and the system reliability is significantly improved. The system has been verified in orbit on some MEO satellites. The effectiveness and high reliability of the design are verified through the analysis of the on orbit operation data.