Random fluctuations of wind power will cause a great negative impact on the normal operation of the power grid，which can be effectively suppressed by an energy storing system.Such being the case，a smoothing control strategy for hybrid energy storage system（HESS）using real-time wavelet transform to allot frequency and two-level fuzzy control theory to adjust the power values of the energy storage system is proposed.The strategy applies a new frequency allocating method creatively using the wavelet transform theory to make rational distribution of hybrid energy storage system's power based on the value of wind power fluctuations' frequency，the super capacitor is used to smooth short-term power fluctuations and the battery is used to slow down long-time fluctuations.A two-level fuzzy control method is proposed and applied simultaneously to modify the power of HESS，which can adjust the charged state of energy storage devices，weaken the influence of the single fuzzy control method for smoothing the output and improve the smoothing effect.Finally，the example results show that the control strategy proposed can rationally distribute the energy storage devicespower and effectively smooth wind power fluctuations while ensuring the state of charge（SOC）of energy storage devices will be maintained within a rational range.It also has a better smoothing effect than the single-level fuzzy control method.