With the continuously growing demand of the voltage-sourced converter-based high-voltage direct current (VSC- HVDC) transmission, modular multilevel converter (MMC) achieves great attentions in VSC-HVDC system. Circulating current eliminating and sub-module capacitor voltage balancing is one of the main technical challenges associated with the control of MMC. The discret mathematic model of the modular multilevel converter based HVDC (MMC-HVDC) system is derived, and an improved model predictive control (MPC) strategy with engineering value is proposed for five-level MMC. The sub-module voltage ripple is reduced by introducing the error factor. Furthermore, the combination of MPC and voltage sequencing algorithm reduces the computation burden, and realizes the transmission power control in MMC-HVDC system, circulating current eliminating, sub-module capacitor voltage balancing. Simulation results validate the proposed control strategy.