Wind power has the characteristics of randomness and fluctuation. In order to reduce the bad influence of wind power fluctuation on the power grid, as well as variation of wind power fluctuation per minute, the smoothing control was usded for the wind power with a first order low pass filter and battery energy storage system. The suitable smoothing time constant was selected according to the smoothing effect of the wind power, the relationship between energy storage capacity and smoothing time constants was analyzed, and the suitable smoothing time constant of energy storage was chosen according to the smoothing rate of energy storage, which could provide the reference for the wind power smoothing control of wind farm with energy storage system.