It may lead to low frequency oscillation in interconnected power grid if part of the lines of power transmission section is disconnected. Reducing the output of generators in sending end urgently is an effective measurement to restrain oscillation, and different control strategies may lead to different effect. The damping of generators’ control system and the electrical distance from generator’s access point to receiving end are the two important factors which impact the effect of cutting machine. The above factors are quantified respectively by damping contribution and phase difference of nodes’ voltage in this paper, and they are weighted to priority order of cutting machine. The damping contribution accumulates the effect of damping torque segmentally by decoupling the electromagnetic torque to synchronous torque and damping torque. The actual power system of North China is used to verify the correctness of the method. By comparing the existing security control strategy with the calculation result of this proposed method, it shows that the method in this paper can optimize control performance and reduce control cost. Therefore, this method has some practical value.