The control strategy of sustained over-voltage during the early stages of power system restoration is studied and a new method is presented in the paper. According to the results of load flow calculation and sensitivity analysis, the method applies expert system technique and non linear programming in turn to solve the control scheme of sustained over-voltage for each target bus. Differences between the early stages of restoration and the normal condition of power system are taken into account. A test to the IEEE 39-bus New England system is included to show effectiveness of the method.