Because wind power generation has strong randomness and volatility, its large-scale grid connection will lead to the reduction of inertia of the system, and the anti-interference ability will also be weakened. Electrochemical energy storage is a high-quality regulatory resource, which has been widely used in all aspects, and business cases show that it can effectively smooth wind power fluctuations. At present, most studies consider the case of hybrid energy storage system or energy storage and other entities participating in wind power fluctuation calming. Although the calming effect is better, the coordinated control between multi-energy storage system or multi-entities is more complicated. Therefore, this paper proposes a two-stage power optimization allocation method for a single energy storage system to smooth wind power fluctuations, which is mainly divided into pre-day stage and intra-day stage. The pre-day stage determines the charging and discharging power of the energy storage in the next day with the goal of maximizing the income of the energy storage and wind farm station. At the same time, the total power of energy storage and wind power must meet the requirements of the grid fluctuation limit. The simulation results also show the effectiveness of the two-stage method, which can be applied to engineering examples and has practical significance.