This paper proposed a control strategy of MMC-HVDC system based on the inner current state feedback decoupling control methodology. It established the MMC-HVDC mathematical model in d-q synchronous rotating frame of axes. Afterward, it established a MMC-HVDC dual-loop control system consisting of inner controller and outer controller. Inner controller is realized the track control of d or q axis current references accurately. By the state feedback decoupling control, inner controller is realized the control of d or q axis electric quantity decoupled. It gave the pole assignment for inner current controller to improve its stability. Then inner controller can be simplified as a first order inertia element. By adopted proportional-integral control, outer controller can suit the multiple operation modes of converter. A two terminal MMC-HVDC simulation model is established and simulated in the PSCAD/EMTDC environment. The feasibility and effectiveness of the proposed control method are verified by simulation results.