Abstract: The phytoplankton community， chlorophyll\|a （Chla） and primary productivity （PP） of 26 sampling sites were investigated in the surrounding areas of Sanmen Nuclear Power Station （121°30′～122°0′E， 29°0′～29°20′N） in February（winter）， June（spring）， August（summer）， and November（autumn）， 2012， respectively. 114 species， belonging to 51 genera and 4 phylum， were identified in the research area. The number of species was summer（79）＞spring（62）＞winter（42）＞autumn（36）， and was enhanced from inside to outside of the bay in spatial level. The mean of Chla concentrations was 374 μg·L-1. The variety of Chla in temporal level was according to the following rules: spring（653 μg·L-1）＞summer（487 μg·L-1）＞autumn（204 μg·L-1）＞winter（152 μg·L-1）， but decreased from inside to outside of the bay in spatial level. The mean of PP was 117 μg C·（μg Chla）-1·h-1. The highest of PP was observed in summer ［249 μg C（μg Chla）-1·h-1］， while the lowest in spring［023 μg C·（μg Chla）-1·h-1］. The spatial distribution of PP was the same as Chla.

Key words: Sanmen Bay, chlorophyll\, a, primary productivity, spatial\, temporal distribution