Abstract: In order to probe into the accumulation of heavy metal in the biofilm,and the infection and contribution of the biofilm in the courses of water-sediments exchange,this paper studies the adsorption of mercury and other heavy metal in the biofilm and sediments,and compares the changes of mercury species after the adsorption in these two mediums The result showed the species of mercury and other heavy metal in sediments are mainly the residual matter bound,while the percentage of carbonate bound,ion exchangeable bound and organic acids bound are little The organic matter in the biofilm is much higher than this in the sediments The growth time,illumination and temperature are important factors affecting the heavy metal's content in the biofilm It can be inferred that the stronger the illumination,the higher the temperature,the longer the growth t ime,and much more the content of the heavy metals in the biofilm.q