This paper discusses the application of the BIT technology used in the test system of the launch vehicle. This paper studies the design principle and working mode of BIT technology. We will design the test process of the BIT and applies it to the launch vehicle test system. By using the big data to research in the process will reduce the false alarm rate dramatically. It is of great significance for the launch process of the launch to improve the reliability of test, the efficiency of fault detection and the fault isolation-elimination.