Direct current/Direct current (DC/DC) converter is an important component of electric vehicle (EV) charger, and also one of the main interference sources affecting the electromagnetic environment of electric vehicle charger. For the common mode electromagnetic interference (EMI) generated by DC/DC converter in charger, a voltage complementary phase-shifting ZVS-DC/DC full-bridge converter with clamp diode is designed to suppress the common mode electromagnetic interference generated by the converter,considering the electromagnetic interference source and propagation path. First, the working principle of DC/DC converter and its main interference source are analyzed. Secondly, the path of common mode EMI propagation of DC/DC converter is modeled and deduced theoretically. Finally, the common mode EMI generated on Matlab is simulated and analyzed. In this paper, the converter circuit after the suppression method is established, and the correctness of the method is verified by simulation. The results show that this method can effectively reduce the common mode EMI of DC/DC converter and improve the electromagnetic compatibility of electric vehicle charger.