The significance and development trend of automatic test system (ATS) in the field of testing and maintenance of electronic equipments are discussed. The significance of test program set (TPS) in ATS is introduced. The structure and function of TPS and general testing platform are described. Taking the video output equipment for example, the tested unit interface adapter (TUA) is designed based on the testing requirements. And the testing programs (TP) are designed by the means of the combination of TestStand and VC++. The practical operation results show that TPS has the capabilities of function testing, fault diagnosis and isolation for video output equipments.