Abstract: The primary frequency regulation reserve capacity of large-scale multi-wind farms connected to the power system is taken as the research object. Firstly, the uncertainty factors of the system are described by introducing the probability distribution of wind power output prediction error, and the minimum total cost of primary frequency regulation reserve of wind power and energy storage is considered as the goal. Then, a capacity optimization model of multi-wind farms joint sharing energy storage participating in primary frequency regulation based on chance-constrained programming is established. Finally, an improved p-effective point method based on a fast Fourier transform to quickly solve the probability distribution of joint variables is proposed to transform the chance-constrained programming into deterministic programming through mathematical analysis. Then Cplex is called by Yalmip to realize the fast solution of the model. The results of the example show that the proposed model and method can effectively improve the effect and benefit of windstorage frequency regulation, and have higher solution efficiency.