In this study, bacteria strains of sewage in pig farm were isolated and screened from rotten manure, straw and other decomposed areas. Cellulase, protease, lipase, amylase and acid-producing microorganisms with high enzyme activity were used as indicators to identify bacteria as Bacillus thuringiensis by 16S rDNA analysis. Through NCBI system comparison, the phylogenetic tree was constructed to determine the species. Taking pig farm sewage as an example, the effects of isolated and screened strains on COD, BOD₅, TP, TN and SS were evaluated. The demonstration results show that the aerated aeration method can effectively reduce water pollutants. The degradation rate of each index is COD 52.9%, BOD₅ 60.5%, TP 44%, TN 35% and SS 62% respectively.It was proved that adding screening strains and aeration with oxygen could effectively reduce water pollutants, which laid a foundation for further application.