Abstract: The distribution,accumulation and transfer dynamics of PCB1254 in water,sediments and biota in a simulated micro-cosmos system were studied. The results showed that PCB1254 released into water body were mainly absorbed upon the surface of suspending particles or precipitated into the sediments due to its high octanol-water partition coefficients(Kow),the concentration of PCBs dissolved in water was very low. The increase of organic material content in water would lead to transfer of PCB1254 from sediments to water column,The distribution and equilibrium of PCB1254 between the water column and sediments phase were related to the organic materials contents such as excrement of fish and shellfish,remnants of life. The extent to which PCBs enter biota is highly dependent on the physical and chemical properties of the compounds and the metabolism capacity of organisms.There were differences in the distribution,accumulation and transfer dynamics of PCB1254 for different organisms:Echinodorus amazonicus adsorbed the PCB1254 mainly by its leaf instead of its roots with a way of physical absorption to some extents and very quickly reached to the equilibrium;Corbicula fluminea had obviously the accumulation of PCB1254,especially in visceral tissue,increasing continually during the 45-day experiment. For Hypophthalmichthys molitrix,the significant differences of PCB1254 accumulation existed between gill,visceral and muscle tissues. It is higher in visceral and muscle than in gill,indicating that the accumulation of PCB1254 was closely related to the content of lipids in different tissues. It is the highest in BCFs(Bioconcentration Factors)of PCB1254 in the visceral tissues of Corbicula fluminea. In which BCFs was about 89418 times,followed by Hypophthalmichthys molitrix,lowest for Echinodorus amazonicus with BCFs(7648.9 times)