In order to improve the dynamic response speed of the inner loop of the HVDC transmission system based on modular multilevel converter (MMC-HVDC), a model predictive control method (MPC) for MMC-HVDC system is proposed. In this method, the optimal control voltage is obtained by predicting model, feedback correction and rolling optimization. MPC overcomes the problem of PI parameter tuning difficulties and slow dynamic response of traditional double closed loop control. In view of the outer loop PI controller parameters on the system sensitivity problem, the parameters of PI controller are adjusted adaptively. The robustness of the controller is improved by adjusting the PI parameters according to the input error and the output of the controller. In order to realize the voltage balance between sub module capacitor, the NLM voltage balance modulation algorithm based on the ranking method is adopted to realize the capacitor voltage balance between the sub modules. At last, the simulation model of 5 levels MMC-HVDC system is built on Matlab/Simulink platform. The simulation results show the effectiveness and feasibility of the proposed control strategy. This work is supported by Fundamental Research Funds for the Central Universities (No. 2682014CX028).