Energy storage system is one of the key technologies of electric vehicle promotion. A single storage battery can’t meet the power demand of the electric vehicle, so the speed of electric vehicles can’t be improved, limiting the development of electric vehicles. Therefore, the energy storage system of electric vehicles must be combined with two or more kinds of energy storage structures to form a hybrid energy storage system, giving full play to the advantages of various energy storage technologies. In this paper, a hybrid energy storage system consisting of battery and super capacitor is used to meet the two demands of electric vehicle's power and energy simultaneously. The hybrid structure can switch between Battery/SC and SC/Battery working mode, the control is more flexible, but it increases the difficulty of energy management of hybrid power. The operating mode of Hybrid Energy Storage System of battery and super capacitor is not conducive to optimal power allocation of different operating modes. A HESS power hierarchical management optimised strategy has been proposed. The working mode of HESS is discussed hierarchically, an optimal mode of output power of energy storage system is set and energy management strategy is designed based on different hierarchies. Genetic algorithm is utilised to optimise power allocation in order to improve the overall efficiency of the system on the basis of hierarchical energy management strategy. HESS simulation mode and experiment platform are built to simulate and experiment, the result of simulation and experiment show that, under the road condition of EUDC and UDDC, optimised HESS using the genetic algorithm can reduce 1.1% and 0.8% of the overall loss compared with that of the traditional hysteresis control. The optimised HESS using genetic algorithm can effectively reduce the loss of the system, realise power optimal distribution. It can also follow the demand of power in time and the super capacitor compensate or absorb peak power to ensure battery safety.