Abstract: The seasonal variation of residual currents in adjacent waters of Daya Bay was analyzed based on the longterm current data observed by HF Radar with T_tide toolkit. The results showed that the variation of residual current in adjacent waters of Daya Bay was mainly the types of winter and summer and it changed synchronously with monsoon. The residual current flowed southwest in winter, which lasted from October to March of the next year, and the current velocity had reached more than 30 cm/s. While the residual current flowed northeast in summer, which lasted only from May to August, with velocity up to 23 cm/s. The seasonal variation of residual currents was not only correlated with wind, but also significantly correlated with the seabed topography. Besides, the east Guangdong coastal current and the Pearl River diluent water had regulating effect on the spatial distribution of residual current in adjacent waters of Daya Bay.