In this paper,heterotrophic nitrifying bacteria(Acinetobacter bereziniae Zhi77)was isolated,screened and identified from pig farm sewage.Immobilized nitrifying bacteria were obtained by calcium chloride(CaCl2)and so-dium alginate(C6H7NaO6)reagents.The effects of culture temperature,strain addition and strain reaction time on the nitrogen removal efficiency of immobilized strains were analyzed.The results showed that the removal rates of ammo-nia nitrogen and TN reached 95.73% and 80.43%,respectively,under the condition of 30℃,2 mL strain addition and 12 days of culture.Under the synergistic effect of COD degrading bacteria and immobilized heterotrophic nitrify-ing bacteria,the removal rates of COD,NH4-N,TN,SS and TP in the treatment group with microbial addition and aeration were significantly increased,reaching 87.90%,96.08%,94.50%,82.70% and 23.64%,respectively.The concentrations of various pollutants in the pig farm sewage were significantly decreased,which has good application prospects in the field of livestock farm sewage treatment.