According to the present situation of the main river pollution in Nanchang City, based on the characteristics of the water quality of the main river in Nanchang city, Yudai river and the old river of Fuhe river， the dominant nitrifying bacteria and phosphorus accumulating organisms(PAOs) bacteria were screened out，and the superiority strains immobilized degradation effect of ammonia nitrogen and total phosphorusin in Nanchang city rivers was studied. The results showed that the degradation rate of nitrite nitrogen by nitrifying bacteria XH3 was up to 100%, that of nitrifying bacteria YH3 was 82.75%, and the degradation rate of total phosphorus by PAOs JP2 was 58.57%. The dominant strains XH3, YH3 and JP2 were proportioned according to the mass ratio of 1∶1∶1, and the degradation rates of ammonia nitrogen and total phosphorus rate reached 85%, 22.86%, respectively. Using PVA+ additives, the immobilized carrier of dominant strain was prepared and used to study the degradation effect of ammonia nitrogen and total phosphorus in Nanchang river under aeration 24 h. The results showed that the carrier can effectively reduce the ammonia nitrogen and total phosphorus in the Nanchang river by 82.70 and 79.27%. The method provides a feasible and effective way for the improvement of the river in Nanchang city.