To reduce the phase lag existing in the control process of energy storage system（ESS）in the photovoltaic fluctuate suppression scenario, an innovative ESS controller based on second-order filtering is proposed. The effect of the phase delay characteristic of the traditional smoothing filter on the ESS capacity is analyzed. The larger the phase delay is, the greater the ESS capacity demand is. In order to eliminate this effect, the lowest order of the controller that can eliminate phase delay is the second order, and an ESS controller based on the second order filter is derived, and the control parameter design method is proposed to effectively reduce the phase delay in the smooth control process and minimize the ESS capacity requirements. The controller is simple in design and contains only two control parameters,which can be applied to practical projects. Finally, the power data of a 5MW photovoltaic power station are used to verify the effectiveness and superiority of the proposed ESS controller.