Bringing the potential of generator reactive power regulation into full play and improving the voltage quality of the power grid are key objectives for power system reactive power and voltage control.To improve the power system voltage level，this paper presents an optimization strategy for setting the excitation system adjustment coefficient of the generator.The effect of excitation system adjustment coefficient on power system voltage is studied，and the principle for setting the generator excitation system adjustment coefficient region by region is proposed.An optimization model is developed with the voltage fluctuation index minimum as the objective function，and the power-flow constraint equations and the excitation system adjustment coefficient as control variables.The particle swarm optimization（PSO）algorithm is used in finding the solution.The case studies of Jilin province power system show that the optimization strategy is meaningful in improving the quality of the power system operation voltage and the potential of generator reactive power regulation.