Abstract: This paper built an electromagnetic transient mathematical model of modular multilevel converters（MMCs） and dynamic model of DC voltage in high voltage direct current（HVDC） transmission that adopts MMC as converter.Based on it,the dynamic characteristic of DC voltage in HVDC transmission was analyzed,and HVDC control system parameters coordinated design principles and its algorithm were proposed.Finally,the correctness of proposed submodule capacitor voltage balancing scheme,MMC based HVDC control system parameters coordinated design principles and its algorithm were verified by digital simulation based on PSCAD/EMTDC.