Abstract: Wind power is one of the most mature power generations which is with reliable potential for commercial deployment in the field of renewable energy utilization. Large-scale offshore wind power grid interconnection issues are now becoming the focusing topic in the field of wind power developments and grid interconnection researches, because of the abundant wind resources of and the urgent engineering practices requirements to offshore wind power. Several key technologies regarding power transmission and grid interconnection were presented, including offshore wind power transmission, design for offshore wind farm substation and collection system, forecasting technology for offshore wind power, active/reactive power control technology of offshore wind farm cluster and stability control technology. The research status and key finding of the above mentioned technologies were summarized. The development trend and the research direction for further study of offshore wind power were also figured out, which provides a reference for the development of offshore wind power grid interconnection.