Based on equivalent model of power network and voltage stability index, a coordinated voltage stability control scheme is developed in this paper. According to the relationship between power transfer capability and grid-side voltage source potential of two node power system, power network equivalent model is used to study on voltage stability control, and it is proposed that the control function is achieved by regulating system-side equivalent potential. More, a voltage control model and algorithm is presented, in which the control nodes are decided by considering effectiveness and control capability of voltage source nodes, and the control inputs are obtained by solving a simple optimized problem. Based on this idea, a coordinated voltage control strategy and on-line implementation scheme is provided. Simulations conducted on typical power systems indicate that the voltage control scheme can keep voltage stability margin and voltage level effectively.