In this paper, the distribution of feal coliform bacterial and heterotropic bacteria in Hangzhou Bay, and the relationship between the biological abundance and the environmental factors have been resarched based on the data got from the field, May to June 1999. The results show the distribution of feal coliform bacteria with charateristics of the northwest higher and southeast lower, which mainly influenced by continental matter, while the distribution of hetorotropic bacteria in the east was higher than the southwest and actively coincidence with phytoplankton in the bay. Furthermore, the analysis of correlation between the bacteria and the environmental factors showed that feal coliform bacteria and heterotropic bacteria have obvious relativity with inorganic phosphorus and chlorophyl a respectively beside both of them were actively coincidence with water temperature and salinity.