Abstract: This paper presents a dispatching strategy of active power based on Matrix Perturbation Theory ( MPT) for multi-machine 2 to enhance the minimum damping ratio, while can avoid burdensome deviations calculation of damping ratio. In this method, the damping ratio sensitivity is deduced through MPT, which needs not to consider derivation of specific formula. While considering sensitivity matrices, a calibration model is established to regulate the output power of generating units to improve the minimum damping ratio of the power grid. Simulation results on IEEE 9-bus, IEEE 39-bus and the southern area 634-bus systems show that the proposed method not only can improve the stability of 2, but also avoid burdensome deviations calculation and improve computational efficiency.