The large receiving end power grid with characteristics of UHV AC/DC mixed was prone to a cascading failure.In the event of HVDC pole blocking,frequency stability problem may occur.For multiple dc coordination control,pumped storage control,accurate load control and other frequency emergency control methods,this paper conducted frequency emergency control characteristic simulation based on the actual power grid model.The simulations verified the effectiveness of the existing frequency emergency control methods.And specific improvement measures were also put forward.