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 sodium 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 ammonia nitrogen and TN reached 95.73% and 80.43%, respectively, under the condition of 30°C, 2 mL strain addition and 12 days of culture. Under the synergistic effect of COD degrading bacteria and immobilized heterotrophic nitrifying 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.