The primary production and potential fishery production in the sea area around the Daya Bay Nuclear Power Station (DBNPS) before and after it’s operation of DBNPS were analyzed based on the surveys in 1992 1993 , 1994 -1995 and 1998. Furthermore , the environmental factors which would affect the primary production were discussed. The results show that the mass of phytoplankton , primary production and the annual yield increased distinctly after the operation of DBNPS , and the factors affecting the primary production was water temperature before it’s opperation but transparency after.