Abstract: While electric workover rigs runs, the current of grid-connected transformer is usually over its rated current. It is serious to endanger to its safety operating. The control strategy of super capacitor energy storage system with grid-connected transformer protected is proposed. The mode switching is designed to regulate 6 operation modes, which is controlled by program. The over-current protection of grid-connected transformer is thought as the primary control, and the capacity regulating control as well as DC bus voltage stable control are completed. Not only the grid-connected transformer running safety is ensured, but also the workover rigs feedback energy is absorbed quickly. These electric energies are saved and utilized again. Based on the PSIM simulation platform, the proposed control strategy is adopted. The simulation of the super-capacitor energy storage control for electric workover rig is executed. The results verify that the presented control method is correct, feasible and effective.