Aiming at the needs of S-band TT C equipment failure diagnosis and health management, the paper put forward a method of software architecture of failure diagnosis system, the design is given about LNA+D/C equipment condition evaluation for failure diagnosis based on failure tree analysis. The paper based the system of failure diagnosis and health management on the monitoring message of alternative assemble and module. We can utilize the integrated result of automatic test and calibration, collect the working state in total system, and diagnose the equipment. It is realized for prognosticate health condition of equipment and ability to the mandate assessment of task. The system provides the basis of decision-making for resource scheduling.