Abstract: To improve system global voltage stability and ensure operation security of power system, it is urgent to study online real-time monitoring of system voltage level and the dynamic voltage-reactive power coordinated control method. In this paper, by using voltage stability index that has ideal accuracy and linearity based on the measurement information of PMU, the multi-objective optimal power flow model is proposed by considering system network loss and voltage stability margin based on synthetical membership method. This model can effectively improve the global voltage stability by assigning higher optimization priorities for branches in low voltage stability area. Meanwhile, the weight indexes of objective function are determined to distinguish the important degree of system economic efficiency and voltage security according to different system operation status. In the end, simulations are carried out in IEEE-14 and IEEE-57 bus systems and the result verifies the correctness and the effectiveness of the proposed voltage and reactive power control model and strategy.