Aiming at the real-time distribution of output power of lithium battery and ultracapacitor hybrid energy storage system, in order to improve the accuracy of policy control and prolong the service life of battery, a fuzzy control strategy based on parameter improvement is designed to manage the power of the electric vehicle hybrid energy storage system in this paper, so as to rationally allocate the power of the lithium ion battery and the supercapacitor. A dynamic power model is established based on the real-time charging state of the hybrid energy storage unit. In this method, the power model and the physical quantity of input parameters are unified, and the real time maximum allowable charge discharge power and the system demand power are taken as input parameters, and the more accurate fuzzy control rules are Formulated, thus the power distribution of fuzzy control is realised. The experimental platform is built through the Arbin battery test system, and the fuzzy control strategy with improved parameters is compared with the traditional fuzzy control. The experimental results show that the fuzzy control system improved by the parameters is stable, the average current amplitude of lithium battery is reduced by 5% per unit time, the energy consumption of the battery is reduced, the characteristics of the supercapacitor are better played, and the working efficiency is improved. It can extend the service life of lithium battery, and the input volume is all power value. It is easier to compare and classify, and has higher accuracy for meeting the system power requirement.