With the improvement of lean operation demand of power grid, continuous regulation control technologies such as direct current emergency power support, rapid power generation, and load control have received more and more attention in the current power grid operation control. In view of frequency problem under increasing scale of new energy and ultra high voltage direct current(UHVDC), control requirements for different stages of frequency after the fault are analyzed. Then coordination principle and frequency emergency coordination optimization control measures which consider response characteristics, cost, as well as quantitative index of transient frequency security margin are proposed. The cost of frequency control after fault is reduced through coordination of continuous and discrete control measures which also meets the requirement of modern power grid optimization frequency control. Based on actual UHVDC sending-network, feasibility of the proposed method is verified.