Abstract: In allusion to such problems as excessive regulation pressure of automatic generation control (abbr. AGC) units in traditional two-stage dispatching after grid-connection of wind power and higher unit regulation expenses because of not considering control performance standard (abbr. CPS) assessment index in common multi time-scale dispatching, by means of analyzing actual frequency data of power grid it was found that on longer time scales the positive and negative change of the mean value of system frequency deviation possessed the regularity. Therefore, under the CPS index a multi-time scale optimization scheduling model, in which the characteristic of the system frequency deviation was considered, was proposed. The validity of the proposed model was verified by the simulation on Matlab platform. Simulation results show that by means of predicting that the symbol of system frequency deviation will be positive or negative under longer time scales in the future, the proposed new dispatching model decreases the regulated output of non-AGC units at the critical moment of intraday and realtime dispatching phase, and comparing with existing models, the proposed model can make the power grid satisfying CPS assessment criteria and at the same time the regulating stress of AGC unit can be relieved and the comprehensive operating cost can also be reduced.