By now Dalian VSC-HVDC Crossing-Sea Project has the highest voltage level and the largest power transmitting capacity in the world. In the design of VSC-HVDC power system, the main circuits scheme, control strategy, the technical parameters of main circuits and main equipment, insulation coordination scheme and equipment insulation level are proposed for its converter station. Thus the overall VSC-HVDC technical scheme has been formed, which could provide completed design method and ideas for the system design of similar projects, and has special significance for the progress and engineering application of VSC-HVDC technology in China. Moreover, the system design of VSC-HVDC power transmission project has attached significant importance for the development of VSC-HVDC technology, the research of VSC-HVDC equipment and the engineering construction in China.