In order to meet the rapid adjustment needs of power grid operation after accidents,a new model of transient stability constrained optimal power flow (TSCOPF) is established.The model is to achieve the objective of minimum power adjustment.Furthermore,variable step strategy is adopted to adjust the steps of before and after clearing fault separately.The objective of the model is closely related to the degree of system instability.It solves the problem that the power adjustment of the traditional TSCOPF is too large.To ensure that the fault cleaning time and simulation end time can be simulated accurately,the two stages of the variable step strategy makes the numerical method reach the key time with integer steps.Primal-dual interior point method is used to solve the problem.Numerical simulations on the three test systems,IEEE-9,NE-39 and IEEE-118,have shown that the proposed method is helpful for dispatchers to deal with accidents quickly which improves the practical level of TSCOPF.