A grid of 22 stations,giving a broad geographic coverage of the Bohai Sea and the Bohai Strait was selected.Undisturbed sediments were collected from sampling stations during cruises in June 1997,in September/October 1998 and again in April/May 1999.Based on the results of Juario (1975),the average biornass,0.404 g/(m2·a) of meiofauna (including nematode,harpacticoida,bivalve larvae,polycheata and kinorhyncha) in the Bohai Sea is given and accounts for 4.5 percent of the macrofauna in the Bohai Sea.The horizontal distribution of the biomass of meiofauna showed that it was higher at the stations of middle east part of the Bohai Sea and the strait in 1998 and 1999 cruises and it decreased at the stations near to the strait mouth and increased at Station B1 in 1999 cruise.The annual average production in the Bohai Sea is 3.636 g/m2 calculated in term of the formula P=9B.Compared with the biomass of other sea areas in the world,the biomass of the Bohai Sea is similar but slightly lower.The individual average dry weight of nematodes given by different authors is analyzed.