Abstract: Electrochemical energy storage is one of the effective resources to improve the flexibility and stability of power grids with high proportion of renewable energy. A joint optimal dispatch model with multi-resource participating in multi-ancillary services containing hundred-megawatt-level of large-scale electrochemical energy storage in the power grid is established. On the basis of designing the dispatch principle of energy storage participating in dual ancillary services which are peak shaving and frequency response, the problem of multi-time scales cooperative dispatch is solved. By analyzing the influence of control parameters of energy storage on frequency response, the control parameters of energy storage are selected, and a simplified optimization model of joint dispatch is proposed. Using the iterative idea, the nonlinear optimization problem is transformed into a two-stage solution of the main-problem and the sub-problem. The case results show that the proposed optimization method of hundred-megawatt-level energy storage participating in dual ancillary services of power grids can make full use of energy storage resources. While improving the safety of frequency, this method enhances the capacity of renewable energy consumption and improves the economy of system operation.