This paper deals with the microbial ecological structure and purification function of the multi-stages biosystem. The results show that the microbial ecology of the system is a bacteria-algea symbiotic system and bacteria play an important role in the system.The bacteria genus increase with the increase of stages, but the biomass decrease with it. The microbial of the system degraded oil and phenol strongly and resisted the toxic of heavy metals to some extent.A new bacteria method is successfully used in t...