Built-in Test (BIT) technique is a important equipment in complex electronic system. In this paper, the CAN bus based on intelligent built-in test technique in complex electronic system was presented to make use of the advantages of CAN bus to solve the problems of communication and reliability of the distributed intelligent BIT system. This paper elaborates the structure of intelligent BIT system and the fault-detection technique, and the nodes in intelligent BIT system are equipped with the CAN bus interface. It also describes the software and hardware design of intelligent BIT node. The high-speed communication and reliability of CAN bus facilitate the communication and timely disposal of the testing signal and the intelligent BIT design. Experiments and practical applications approved that this technical method was feasible and effective.