This paper summarized the microbiology progress of phosphorus accumulating organisms ( PAOs) in enhanced
biological phosphorus removal ( EBPR ) system, introduced the involved PAOs species classification and biological
characteristics and concluded the techniques for identifying PAOs microbiology,including traditional pure culture technology,
staining and microscope technology, modern molecular with extensional techniques and the combination of various
technologies; the application of molecular techniques was analyzed. This study mainly introduced the progress of
accumulibacter morphology and metabolic characteristics, and discussed the study and developing direction of PAOs
microbiology in the future.