Based on ERA5 reanalysis data from 1979 to 2021, Empirical Orthogonal Function decomposition and Mann-Kendall trend test are used to analyze the spatial distribution, seasonal variation, and long-term trend of the sea surface wind field and wind power density (WPD) in the area associated with the 21st Century Maritime Silk Road. The conclusions are shown below. (1) The WPD in the study area has great spatial differences in different seasons and it is particularly abundant in the Arabian Sea and Bay of Bengal in summer, the South China Sea (SCS) in winter, and the tropical southern Indian Ocean all the year round. (2) In the study period, the overall grade of WPD is high in the north of the SCS and its adjacent waters, the west of the Arabian Sea, the west of the Bay of Bengal, and the tropical northwestern Indian Ocean. (3) The WPD in the study area is mainly characterized by annual variation and it presents the largest seasonal amplitude in the SCS and shows obvious transition features in spring and autumn. (4) In the study area, considering both water depth and evaluation results of spatial-temporal features of WPD, the development and utilization of offshore wind energy resources in the Taiwan Strait, the Luzon Strait, the southeastern coast of Indo-China Peninsula, the west of the Arabian Sea, and the tropical northwestern Indian Ocean shelf seas should be more focused, and the storage of wind energy resources in other waters should be enhanced. This study can provide a basis for the mid-and long-term development of wind energy resources along the 21st Century Maritime Silk Road.