The data from the International Coupled Model Comparison Program (CMIP6) were used to analyze the future long-term variations of wind speed in China Seas and to assess the changes in wind resource distribution. The results show that under four representative scenarios, SSP126, SSP245, SSP370 and SSP585 from 2015 to 2100, the wind speed in the East China Sea shows a significant decreasing trend and the wind speed in the South China Sea shows a significant increasing trend with the increase of external radiative forcing, while the increasing trend in the Yellow Sea and the Bohai Sea are weaker. The wind power density in the northern part of the South China Sea increases significantly in future scenarios, with a maximum increase of 12% relative to historical mean, while that in the East China Sea decreases, with a maximum decrease of 11%. Under the four scenarios, the overall change in near-shore wind power is small, but generally decreases with the increase in external radiative forcing. The wind power density and annual mean wind power in the sea area near the Yangtze River estuary decreases significantly with the increase in external radiative forcing, while that in the Yellow Sea, the Bohai Sea, and most of the South China Sea coasts generally remain unchanged.