Taking the plug- in hybrid electric vehicle as the research object,in order to improve the fuel economy and emission performance,a fuzzy control strategy which can realize the reasonable distribution of demand torque between the engine and the drive motor is designed,and the method of genetic algorithm to optimize fuzzy control rules is introduced in detail. The optimization results show that,the optimized fuzzy control strategy can improve the fuel economy and emission performance compared with the results before optimization,and make the engine working points well concentrated in high efficient area. The research contents will provide operators and experts an effective way to design fuzzy control rules.