The change of phosphorus(P) content in surface seawater is an important parameter to evaluate the nutrient content of Marine ecosystem, and plays an significant role in regulating the evolution of the earth environment. Weizhou Island is the largest and youngest volcanic island in China. The change of surface phosphorus content in seawater is not recorded on a long time scale, and the influencing factors are not yet clear. Coral bone P/Ca is a reliable index for the retrieval of seawater phosphorus content, and is widely used to reconstruct the high-resolution history of seawater phosphorus content. In this study, continuous growing corals in northwest Weizhou Island were taken as the research object, and an age framework was established from 1985 to 2015 based on coral oxygen isotopes to reconstruct the monthly resolution P/Ca change history of surface seawater from 1985 to 2014. The results showed that the coral P/Ca value varied greatly with different years and seasons, and the coral P/Ca value content was low from 1998 to 2003, which was generally lower than the annual average value. The change of coral P/Ca ratio was highly correlated with the change of monsoon (p＜0.5), and the coral P/Ca value increased significantly during the monsoon and typhoon periods, indicating that the sea surface wind was the main factor controlling the change of seawater P content in this region. In addition, volcanic eruptions, oil spills and the development of tourism can also cause a temporary increase in P content, but the effect is limited. However, there was no significant correlation between the inter-annual and wet and dry seasonal variations of rainfall and P/Ca values, indicating that terrigenous materials had limited influence on the change of phosphorus content in seawater.