In order to grasp the structure of the primary production and phytoplankton communities, chlorophyll-a were measured at 39 stations and phytoplankton communities at 10 stations during the period from August 9 to August 21, 2003 in the Barents Sea. The concentration of total, microphytoplankton, and nano-picophytoplankton chlorophyll-a were higher at middle layer than those of surface and bottom. ... Leading organims for the primary production were nano- and picophytoplankton. Phytoplankton communities were composed of diatoms, dinoflagellates, cryptophyceae, silicoflagellate and prymnesiophyceae and showed 53 taxa in surface and 27 taxa in bottom. The first dominant species was picophytoplankton in all station and layers, but the second was 2 and/or 3 taxa. Phytoplankton standing crops ranged from minimum 3.73×105 cells/ℓ to maximum 2.5×106 cells/ℓ, showing some resemblance between surface and bottom. As a results, (1) phytoplankton primary production was more active in middle layer than those of surface and bottom, (2) netphytoplankton species were dominated in surface, but phytoplankton standing crops analogous to each other.