In this paper,a new set of differential-algebraic equations and a secondary voltage control ( SVC) emergency control strategy are proposed to respectively analyze and solve the power system transient voltage stability problem. In this emergency control strategy,the control time constant of SVC is reduced based on normal SVC,the voltage deviation of the bus,which is of the most serious voltage instability after system fault,is introduced in the object function of SVC,and the active set method is adopted to solve the quadratic programming model with the SVC emergency control. Moreover,a simulation model including SVC and primary voltage control ( PVC) is established for the transient voltage stability in power systems in PSAT environment. The correctness and effectiveness of the proposed control strategy and model are verified by the simulation results in the New England 39-bus system.