Abstract: The paper summarizes the biofilm formation and kinetics models in the process of wastewater treatment using bioreactors. The emphases are put on the process of biofilm accumulation,the factors in fluencing biofilm formation,the biofilm structure,and the influences of biofilm structure on the bio-chemical reaction and mass transfer in biofilm. Some typical biofilm models are described, and the research for further development of biofilm-wastewater-treatment technology is also pointed out.