Biofilm not only plays the role of compartmentalization, but also the role of metabolic reaction site, energy conversion site, material exchange site, identification and information transfer. 1. Compartmentalization: Biofilm has the role of dividing and separating cells and organelles. Biofilm not only keeps the cells in a relatively stable internal environment, but also divides the space inside the cells, regionalizes the cells, and forms a variety of organelles, so that the cellular life activities can be divided into compartments. 2. The role of the place: biofilm is the place of metabolic reactions, such as photosynthesis, light energy absorption, biofilm is also the place of cellular energy conversion, such as oxidative phosphorylation, in addition to the biofilm has a selective permeability of substances, can control the exchange of substances inside and outside the membrane. Such as the plasma membrane can be through simple diffusion, active transportation, cytotoxicity and other ways to carry out a variety of substances absorbed and transferred. Thus, the role of biofilm is very important and indispensable for human body.