Macrobenthic infauna and associated environmental factors influencing the benthic community in the eastern coastal region of Shandong Peninsula were analyzed in four seasonal surveys from January 2007 to October 2007 (30 stations in winter,20 stations in other three seasons),in order to understand the community structure and the factors unfluencing the benthic distribution.PRIMER 6.0 and SPSS 15.0 software packages were adopted to analyze the environmental and macrobenthic data.The results show that there were 260 macrobenthic species in total collected from the research region.The composition of species is: Polychaeta (94 species),Crustacea (75),Mollusca (56) and Echinoderm (12),among which,only 23 species were common species in the cruises of every season.The dominant species varied from season to season;however,the polychaete species Paralacydonia paradoxa Fauvel and Echinoderm species Amphioplus japonicus (Matsumoto) were always present year-round.The abundance and biomass of the macrobenthos in the research region were variable from season to season.The results of CLUSTER and MDS analysis show that the similarities of macrobenthic structures between the stations were low;most of the similarities were at about 30% of similarity value,only two stations were up to 70%.In accordance with the similarity values of the macrobenthic structures,we divided the 20 stations into five groups by arbitrary similarity level of 30%.The ABC curve indicates that the marcofauna communities in the research region had not been disturbed massively,except two stations,SB1 and SB3.Ecologically,benthos were controlled by a combination of factors such as salinity,phytoplankton,zooplankton,SiO 3Si and temperature,and no single factor could be considered as an ecological master factor. Macrobenthic infauna and associated environmental factors influencing the benthic community in the eastern coastal region of Shandong Peninsula were analyzed in four seasonal surveys from January 2007 to October 2007 (30 stations in winter, 20 stations in other three seasons), in order to understand the community structure and the factors unfluencing the benthic distribution. PRIMER 6.0 and SPSS 15.0 software packages were adopted to analyze the environmental and macrobenthic data. The results show that there were 260 macrobenthic species in total collected from the research region. The composition of the species is: Polychaeta (94 species), Crustacea (75), Mollusca (56) and Echinoderm (12), among which, only 23 species were common species in the cruises of every season. The dominant species varied from season to season; however, the polychaete species Paralacydonia paradoxa Fauvel and Echinoderm species Amphioplus japonicus (Matsumoto) were always present year-round. The abundance and biomass of the m acrobenthos in the research region were variable from season to season. The results of CLUSTER and MDS analysis show that the similarities of macrobenthic structures between the stations were low; most of the similarities were at about 30% of similarity value, only two stations were up In accordance with the similarity values ​​of the macrobenthic structures, we divided the 20 stations into five groups by arbitrary similarity level of 30%. The ABC curve indicates that the marcofauna communities in the research region had not been disturbed massively, except two stations, SB1 and SB3.Ecologically, benthos were controlled by a combination of factors such as salinity, phytoplankton, zooplankton, SiO 3Si and temperature, and no single factor could be considered as an ecological master factor.