Abstract: Laizhou Bay (37°10′-38°20′N,118°30′-120°30′E) is not only an important spawning site and habitat for fishery resources in the Yellow Sea and the Bohai Sea,but also a traditional fishing site.The results from pair-trawl surveys in different seasons in the area indicate that fishs abundance,diversity and dominance have changed dramatically.The mean catches per haul are 258,117,77.5 and 8.5 kg/h in 1959,1982,1992-1993 and 1998,respectively.The largesized demersal fish,such as largehead hairtail (Trichiurus haumela) and small yellow croaker (Pseudosciaena polyactis) have been replaced by halffin anchovy (Setipinna taty),anchovy (Engraulis japonicus) etc.since the 1980s.The community structure of fishery resources has apparently varied.The continuous releasing penaeid shrimp (Penaeus chinensis) in large-scale has caused the decrease of genetic heterozygosity in the wild stock.The corresponding protection measures to inhabiting environment and biodiversity are suggested based on the analyses of variation of main fishery resources.