Abstract: To solve the problem of the high fault rate of in-orbit operation of satellite, the characteristics of in-orbit operation of satellite are analyzed. The in-orbit operational status of satellite is defined and is correlated with the stabilization of satellite in orbit. Furthermore, the in-orbit fault recognition and diagnosis, the fault strategies, the operational mechanism and procedures for in-orbit management, and the reliability engineering requirements and the technological direction for in-orbit operations are discussed. It is shown that the status transition can be achieved to promote a steady state and the reliability by controlling the operational safe and stable state of satellite in orbit. The article finally proposed the strategy and technology direction to improve the stability and reliability of satellite in orbit.