This paper focuses on the problem of the attenuation of cycle life caused by the high frequency power demand on the lithium ion battery of electric vehicles (EV). First, the working principle of hybrid energy storage systems (HESS) composed of a lithium ion battery, with ultra-capacitor (UC) and multi-port bidirectional DC/DC converter is analyzed, and the relationships among driving cycle tmax, load current adjusting frequency and order of the wavelet decomposition are analyzed. Then an algorithm of Symlets and an Symlets wavelet transform-based power management for HESS are proposed. The proposed Symlets wavelet transform strategy is capable of identifying the high frequency transient and low frequency power demand of the EV, and allocating power components with different frequency contents to corresponding sources to achieve an optimal power splitting. Finally, experiments are performed with the HWFET driving cycle. The results show that the proposed power management method reduces high frequency loads of the lithium ion battery effectively, and decreases the peak voltage fluctuation of the HESS to 51.8% compared to that of the Haar wavelet transform-based power management strategy. This work is supported by the Youth Fund of National Natural Science Foundation of China (No. 61803345 and No. 51807013).