Precise control strategies are the basis of the practical application of superconducting magnetic energy storage system (SMES), which has non-linear dynamic characteristic. In this paper, a novel nonlinear control strategy of SMES is proposed. Mathematic models of SMES consisted of VSC and chopper are established. According to the principle of feedback linearization, the input/output feedback linearization control strategy of SMES is designed. The simulation results show that SMES based on the proposed input - output feedback linearization control has good tracking ability for power instructions and it can quickly stabilize the DC-side voltage of the converter. Simulation results also indicate the validity of the input - output feedback linearization control strategy and it has better robustness and convergence than the typical PI closed-loop control strategy.