Abstract: The infrared earth sensor is a very important part of a satellite attitude control system. Its performance and stability directly affect the security of the whole satellite. Some emergencies happened in attitude control system of China on-orbit satellites usually linked to the interference of infrared earth sensor from celestial bodies. This paper discusses what role the infrared earth sensors plays in satellite and how they are interfered. The results of interference sources analysis are presented here. Finally, some ways to precisely predict when the interference happens and how to overcome them are given. They have been successfully used in managing Chinese on-orbit satellite.