Abstract: In allusion to the impact of grid-connection of large-scale offshore wind power on the operation of onshore power grid and considering the new trend of interconnecting offshore wind power with onshore power transmission system to gradually form the offshore grid, an offshore wind power control strategy based on the unified power flow controller (abbr. UPFC) and the topology adjustment was proposed to control the power flow distribution in offshore power system possessing the interconnection effect, and a bi-layer joint optimal operation model, in which the control of optimal power flow of onshore power grid and the control of offshore wind power containing UPFC and topological adjustment were included, was constructed. Results of computing example show that using the proposed joint control strategy containing UPFC and topology adjustment, the power distribution of offshore wind power among all grid-connection points can be well controlled to implement the requirement of onshore power grid for the power distribution of offshore wind power among all grid-connection points and it is beneficial for friendly grid-connecting offshore wind power into onshore power grid.