Aiming at the problem of insufficient system frequency adjustment capacity under the background of large-scale grid connection of new energy, a system scheduling strategy considering new energy power plants participating in system frequency regulation by dynamic output derating is proposed. Considering the coordination of frequency regulation between new energy with synchronous units, the new energy power plants are taken as the control object. And the reserve power for frequency regulation is dynamically provided by the new energy power plants worked in the state of dynamic output derating. The system frequency constraints under the background of new energy power plants running in the state of dynamic output derating are analyzed, and based on this, a power system scheduling model considering new energy power stations participating in system frequency regulation by dynamic output derating is established. The calculation results based on an improved IEEE RTS 24 bus system show that the strategy can improve the frequency regulation ability of the system and the absorption capacity of new energy and operation economy of the system on the basis of ensuring that the steady-state frequency deviation of the system does not exceed the allowable limit.