Being researched the effect of accumulation of mercury element, under different conditions such as different sampling points, different depth, different incubation time and different temperature etc., which was adsorbed by biofilm which was cultivated in the water of Yellow River. Meanwhile, analyzing the state of existence of mercury. The results show, biofilm has good function on mercury adsorption, and the longer the cultivation of biofilm, the better the adsorption ability. When PH=6，25-30°C，4h, the adsorption ability get the peak.