In modular multilevel converters, the performance of control system strongly depends on the control parameters. It requires a significant amount of testing and debugging to get proper control parameters, which seriously affects the efficiency of controllers. The control strategy of MMC is analyzed and the control system is divided based on the functions. In order to adjust the parameters optimization of MMC controller, the evolutionary state assessment to adjust the PSO parameters is involved, which is to improve the MOPSO algorithm. The electromagnetic transient simulation program is linked to the proposed improved MOPSO to give the results of the optimization objective. This paper realizes the joint invocation between PSCAD and Matlab program, simulation results proof the effectiveness of the proposed method in the parameters optimization of MMC controller. This work is supported by China Southern Power Grid Science and Technology Program:Key Technologies and Engineering Application Research of High-capacity VSC-HVDC (No. CSGTRC-K142031).