Abstract: With the short supply of onshore and nearshore wind power resources, the site selection of offshore wind farms is from nearshore to the deep distant offshore, the scale reaches gigawatt level, and the capacity of offshore wind turbines is developing to more than 10 MW level. For large-capacity offshore wind turbines, this paper firstly describes the development status of key technologies such as capacity, types and converters of offshore wind turbines in China and abroad. Secondly, this paper analyzes the problems and key technologies of the large-capacity three-phase and multi-phase offshore wind turbines, and gives the development trend of topology design and control strategy optimization method of the future multi-phase offshore wind turbines.Finally, this paper summarizes the large-capacity offshore wind turbines.