Objective To obtain capsid p27 of SIV for detecting . Methods The p27 gene of SIV was synthesized and inserted into pMAL-p5x vector to construct pMAL-p5x-p27 recombinant plasmid.And then the recombinant plasmid was transformed into E.coli BL21 to express protein and the express product was purified by Amylose Resin maltose-binding protein affinity column. Results SDS-PAGE analysis indicated that pMAL-p5x-p27 can be expressed in E.coli BL21 and the protein molecular weight was about 70×103Da; The final p27 protein purification could reach 90%. Conclusion p27 of SIV was successfully expressed in E.coli，which lays a foudation for developing the methods of detecting SIV antibody.