To expand the application of Global Navigation Satellite System Reflectometry (GNSS-R) in the field of ocean monitoring, this paper, based on the CYGNSS wind speed products from 2020 to 2023, combined with the wind speed reference data, makes a systematic assessment of the accuracy of CYGNSS wind speed products and analyses the distribution characteristics of wind energy resources in the tropical and subtropical waters of China. Systematic assessment, and analyses of the distribution characteristics of wind energy resources in China's tropical and subtropical seas. The experimental results show that the extrapolated wind speed accuracy of the CYGNSS wind speed product is improved by about 47% after the correction of sea surface roughness, and it has a good matching accuracy with the reference data, which meets the needs of wind energy assessment. In the study area, wind energy resources are more abundant in the southeastern sea, among which the Taiwan Strait has the highest annual average wind power density, reaching more than 550 W/m². In the southern part of the South China Sea, wind energy resources are relatively scarce, and the annual average wind power density is lower than 250 W/m²; the wind power density of each sea area has significant seasonal differences, and the distribution of wind energy resources in the East China Sea is relatively stable in all seasons, with the distribution maintained at more than 300 W/m² all year round, while in the South China Sea there is a more violent seasonal fluctuation, and the difference between the average wind power density of the winter and summer seasons is significant; in terms of the potential for development, the wind power density in shallow waters in the southern part of the Yellow Sea is relatively high. In terms of developing potential, the southern Yellow Sea and other sea areas have high wind energy reserves and technological development capacity in shallow waters, while the northeastern part of the South China Sea and other sea areas show great development potential in deep waters.