This paper proposes a control method of the modular multilevel converter based high voltage direct current (MMC-HVDC) system for the grid voltage stability instead of using a static synchronous compensator (Statcom). The d-axis current component is used to control the grid voltage via the reactive power. Meanwhile, the q-axis current component is employed to control the active power according to its application. With this control method, the power system will operate stably with the maximum efficiency. Moreover, it can save the cost of installing Statcom. The simulation results are performed in the PSCAD/EMTDC software environment to confirm the effectiveness of the proposed control method.