Abstract: Accurate assessment on aquatic biosafety caused by heavy metal pollution in the gulf is of great practical significance for preventing and resolving the ecological risks of marine organisms. Taking Zhanjiang Bay, a typical bay in China, as an example, this paper evaluated the pollution degree and ecological risk of the coastal water of Zhanjiang Bay by using pollution index method, correlation analysis method and species sensitivity distribution method based on the content data of six heavy metals (Cu, Zn, Pb, Cd, As and Hg) in the coastal water surveyed in 2015, 2017 and 2018. The results showed that the Hg content in 36.4% of the water samples in 2015 reached the limit of Class III seawater quality standard, while the heavy metal content of the seawater samples in other years was lower than the quality standard of Class Ⅱ. In 2015, the content of As in shellfish was higher than the Standard Category I of marine life quality standard in China, but less than the Standard Category Ⅱ. While the content of Pb in Philippine clam was higher than the Standard Category I but less than the Standard Category Ⅱ. Heavy metals such as Cd, Cu and Zn still had toxicological effects on sensitive organisms such as algae and crustaceans, up to 4% of the selected species. The research results can provide a scientific basis for environmental protection measures and marine biodiversity protection in Zhanjiang Bay, and at the same time expand the application scope of species-sensitive ecological risk assessment.