Proposed in this paper is a mathematical model to coordinate the parameter optimal design of power system stabilizer（PSS） and static var compensator（SVC）.In this model,the objective function is obtained by weighting both the rotor speed of each generator and the voltage change of the nodes equipped with SVCs,and the inequality constraints are determined as the ranges of PSS and SVC parameters.By calculating the trajectory sensitivities of the rotor speed and voltage change to the control parameters,the gradients of the objective function to PSS and SVC parameters are evaluated,which accelerates the convergence and helps to search the optimal solution.Moreover,by inducing damping power angle oscillation and voltage-reducing factors in the objective function,both the power angle stability and the voltage stability are guaranteed.Simulations in 3-machine 9-bus and 10-machine 39-bus systems show that the proposed method effectively damps low-frequency power oscillation,improves the transient and the small-signal stabilities,and decreases the post-fault voltage fluctuation of the bus.