Abstract: To solve the frequency security problem of a large-scale wind power system during the load restoration period after a blackout, considering the virtual inertia and the primary frequency modulation response process of the wind turbine, a dynamic frequency response model is constructed based on the equivalent swing equation. The analytical expressions of the rate of changes of frequency (RoCoF) and the frequency nadir are derived, which are used as the constraints in the disturbance scenarios. On the basis of these constraints, an optimization dispatch model for the load multi-step restoration is proposed, aiming at maximizing the load restoration and minimizing the operation time. A linearization method of nonlinear constraints is given to improve the efficiency of the restoration decision-making. The case study on the modified IEEE-39 bus system shows that the proposed model can realize the orderly grid-connection for the load and wind power in batches during the recovery process, reasonably dispatching the outputs of the conventional units and ensuring the frequency security and the recovery speed.