Plug-in hybrid electric vehicles are often in start-up and stop state under complex driving conditions. High current pulse has a great impact on the high-voltage bus of automotive electric drive system, resulting in the rising peak voltage of high-voltage bus, which is very easy to cause vehicle safety accidents. Aiming at the problem of high voltage bus overvoltage in plug-in hybrid electric vehicle electric drive system, a Bang-Bang control strategy is proposed to suppress the peak voltage on the high voltage bus. The accuracy of the control strategy is verified in the experimental environment of the overvoltage protection device of the electric drive system. The experimental results show that the Bang-Bang control strategy is adopted. It can effectively suppress high voltage bus overvoltage and ensure the safety of hybrid electric vehicles.