Provided are an apparatus and a method for diagnosing fault and processing data of a satellite ground system. The apparatus and a method can prevent data loss of a satellite, and efficiently operate the satellite ground system using data buffer and penalty method when a temporary fault occurs. Data buffer stores data in fault situation and penalty method imposes high penalty in critical fault and low penalty in minor fault. System is managed according to penalty degree. The apparatus, includes: a satellite data processing and controlling means; a signal transforming means; a fault detecting and controlling means; a state displaying means for displaying a state of the satellite and the system; a penalty managing means for being notified whether the device has fault or not; a data storing means for storing and transmitting the data; and a system recovery supporting means.