A highly effective aerobic denitrification strain was screened from the municipal activated sludge and its gene sequence was obtained from DNA extraction and amplified by the polymerase chain reaction (PCR) amplification. Based on the result, the strain was preliminarily identified to be Pseudomonas by way of comparison with the National Centre for Biotechnology Information (NCBI) Genbank. In order to get more knowledge of the aerobic denitrification strain and its application in wastewater treatment, the strain was added into the membrane bioreactor (MBR) to construct a denitrification MBR (dMBR) for municipal wastewater treatment due to its high denitrification ability. The experiment results showed that nitrogen removal efficiency was as high as 80% in dMBR and nitrogen removal efficiency was 50% in the control MBR (cMBR), which indicated that aerobic denitrification in the MBR tank played a main role in removing the nitrogen under aerobic conditions. The best strain dosage was 20-30% in the total activated sludge. The dMBR also had a better membrane fouling resistant effect than cMBR. As a result, the dMBR could be an effective method for nitrogen removal of the wastewater treatment.