In order to realize the optimal control of modular multilevel converter (MMC), a model predictive control strategy based on voltage level for MMC is designed. Based on the sum and difference of arm voltages, the mathematical model of MMC system is derived. Then a model predictive controller with hierarchical structure is designed by the mathematical model. The cost function design in the controller takes into account the AC side current control, the circulation current suppression and the arm energy balance. The cost function also selects the optimal voltage level to provide a voltage reference for the pulse width modulator. In addition, submodule capacitor voltage balancing is accomplished with a separate control loop. Finally, the hardwareintheloop simulation test system for MMC is built. The steadystate and dynamic test results verified the effectness of the new control strategy.