Abstract: Spatial distribution characteristic of Phytoplankton community and their correlation with environmental factors in Sanmen bay, East China Sea were studied based on the dataset of our field investigation in spring and summer 2014 using multivariate statistical techniques.Results showed that a total of 82 species were identified during the two sampling seasons, including 46 species (4 phyla) in spring and 64 species (4 phyla) in summer respectively.A significant seasonal variation was found in terms of phytoplankton abundance and dominant species.According to the results of redundancy analysis (RDA), the controlling factors influencing the phytoplankton community were salinity, water temperature, dissolved oxygen, dissolved inorganic nitrogen and suspended solid in spring, while total organic carbon, silicate, water temperature, dissolved inorganic nitrogen, suspended solid, salinity and phosphate were the primary variables in summer.