Abstract: Grasp the characteristics of pandemic strain of the South Xinjiang PRRSV, provide a theoretical basis for the effectiveprevention and control of the South Xinjiang PRRS. In this study, five complete sequences of ORF3 genes of the South Xinjiang PRRSV wereobtained by cloning and sequencing and sequence analysis. The results showed that the gene length of five complete sequences of ORF3 genes ofthe South Xinjiang PRRSV were both 765 bp, nucleotide homology between them was 90.3% to 99.5% ；The nucleotide homology of ORF3 geneswith LV of Europe type represents strains, ATCC VR-2332 of American type represents strains, CH-1a of China type represents strains, JXA1 ofthe HP-PRRS China type represents strains, attenuated vaccine strains used wildly in Chinese pig farms was 61.2% to 62.2%, 88.6% to 89.2%,92.5% to 95.8%, 90.5% to 99.2%, 87.8% to 99.6%, respectively ；The amino acids homology of ORF3 genes with the American type strainandand Europe type strains was 80.3% to 99.2% and 53.5% to 55.1% ；The five ORF3 genes of the South Xinjiang PRRSV were both belongs to theAmerican type subgroup II strains. The molecular epidemiology investigation result of the South Xinjiang PRRSV for the choice of vaccine forSouth Xinjiang PRRS made a further adjustment or guidance.