Abstract: Dajin Island waters is one of habitats of Indo-Pacific humpback dolphin. Concentrations of heavy metals in sea water,sediments and organisms（fish,crustacea and cephalopoda）at the habitat were analyzed. The results showed that the sea organisms have obvious enrichment to the heavy metals in coastal waters, high concentrations of heavy metals in the liver of Indo-Pacific humpback dolphin is accumulated grade by grade in food chain. The environment quality of the habitat is evaluated. It is indicated that the water quality in this habitat is between the first and the second rank, sediment quality is the first rank, and the heavy metals in three kinds of organisms are all lower than the standard. It also indicated that the marine area hasnt been polluted by heavy metals. The environmental quality in this water area is fit to Indo-Pacific humpback dolphin s living. Heavy metals level at the Dajin Island waters is in the low value section of the Pearl River estuarine zoon, it may be an important reason of Indo-Pacific humpback dolphins selecting this area as their habitat.