Abstract: Automatic fault diagnosis and health management has become an important function of ground-based radar, high quality testability design is the basis of realizing the function. The testability design of ground鄄based radar includes three levels: system,subsystem and module. Aiming at the system level testability requirements of ground-based radar, the design flow of system level testability, the design method of the system built-in test and the design method of central test system are proposed. The system function test and fault isolation scheme of a new type of digital array radar are introduced. The design method proposed in this paper can be used to improve the design quality of ground-based radar.