Abstract:The study was based on the investigations of fishery resources and environment of the Bohai Sea in 1982 and 1992. Using the EwE modeling software, the mass-balance models of the Bohai Sea ecosystem during the two periods were constructed. Based on the two models, the changes of the Bohai Sea ecosystem structure and fishery resources between ten years were compared and analyzed. The models included 17 functional groups covering the main trophic flow of the Bohai Sea ecosystem, which were Japanese anchovy, Scaly hairfin anchovy，Japanese Spanish mackerel，other pelagic fishes, small yellow croaker, seabass, benthic fishes, other demersal fishes, zooplankton, phytoplankton, detritus, etc. The results indicated that the total biomass of 1992 was lower than that of 1982, and small sized pelagic fishes have become the main components of the fishery resources in the Bohai Sea in 1992, and the proportion was obviously higher than that in 1982. Since the catch of lower trophic level fishes increased in 1992, the mean trophic level of catch declined. The Bohai Sea ecosystem in 1982 and 1992 were both in developmental stage, and the system scale in 1982 was greater than that in 1992. From 1982 to 1992, the changes of the Bohai Sea ecosystem structure were mainly due to the decrease of primary production and increase of fishing pressure. Since there was high surplus production, the recovery of depleted fishery stocks and increase of fishery resources may be possible and high potential if the rational conservation measures were applied.