Abstract:Built-in Test (BIT) is that the systems or equipment have the ability to detect and isolate faults automatically by themselves, and it is an important technology that can significantly improve the testability and diagnostic capability of the system. BIT has the advantages of high detection efficiency, low cost and that it can test the system, modules and components hierarchically, which makes it has wide application prospect in areas such as aerospace, electronic equipment, weaponry and so on. In this paper, the worldwide research and development of BIT were analyzed and summarized firstly, and then various structure principles, advantages and disadvantages were analyzed. Meanwhile, the false alarm reducing strategies of BIT were overviewed. Finally, the characteristics of BIT were summarized, and its future trends were also discussed.