Abstract: The multiplication of denitrifying，phosphorus removing bacteria (DPB) in the anaerobic stage of A2/O and species/function change of the bacteria before and after inducement were studied. After multiplication，the amount of denitrifying，phosphorus removing bacteria increased from 4.1×103 cell·mL－1 to 2.7×106 cell·mL－1. The removal efficiency of phosphate increased from 38.5% to 95.1%. After inducement four Pseudomonas sp.，two Enterobacteriaceae sp.，one Aeromonas sp.，one staphylococcus sp. and one Agrobacterium sp. were isolated. The Pseudomonas sp.， Enterobacteriaceae sp. and staphylococcus sp. belonged to simultaneously DPB，but the function of Pseudomonas sp. was the best，Enterobacteriaceae sp. was middle，and staphylococcus sp. was the worst. Aeromonas sp. and Agrobacterium sp. belonged to phosphorus accumulating and denitrifying bacteria，but were not simultaneously DPB. The identification of simultaneously DPB must accumulate phosphate and deoxidize nitrate simultaneously.