CAN communication is a relatively common communication method used in the industrial and automotive fields. It analyses the main cause of communication interference in the electromagnetic interference phenomenon of CAN communication in industry. Due to factors such as circuit imbalance and space electromagnetic field, the CAN bus will cause common mode interference due to radiation. The strong interference generated in the field may cause the relay to malfunction and cause the wrong signal. Therefore, this paper proposes protection measures against the malfunction of the relay from the perspective of signal input and relay triggering, and has strong anti-interference ability after testing in actual projects.