Abstract:The characters and effects of sea land breeze in Yangjiang were studied. The ba sic data were taken from weather stations, automatic weather stations in Yangjia ng and two towers of 80 metre high gradient observation on the seaside. The re sult shows that the western coast sea breeze formed earlier than the eastern coa st one. In surface layer, the sea land breeze increases with height. Sometimes in May, the sea land breeze is too weak to reach the height of 80m. The change from land breeze to sea breeze occurs mostly during 11:00-12:00. On th e contrary the change from sea breeze to land breeze happens at about 23:00, both dur ing the period of daily peak of pressure fluctuation. The sea land breeze can r each 70-75 km far from the coastline when it superimposes valley wind, but it ca nnot pass over the Mist Hill. During the period of sea land conversion, a conve rgent zone formed near the bay, which made the urban district of Yangjiang at it s northern side to be a rainy center from April to July. The sea breeze converse d in the pipe socket area near Yangchun and made this region become another rain y center. All above are important factors making Yangjiang to be the rainy cente r of Guangdong. In addition, if the sea-land breeze circulation was not broken down, Yangjiang coastal areas would not have high temperature weather.