The full-length cDNA of the soybean seeds was obtained by RT-PCR, and amplified by self-designed primers to obtain the target gene α_c, The target gene was linked to the vector to construct a recombinant cloning vector pGEM-α_c, which was identified by double digestion with XhoⅠ/EcoRⅠ and ligated with vector pET-28a to construct a recombinant plasmid pET-28a-α_c. After correctly transferred into competent cells E.coli BL21 (DE3), the recombinant protein of α-subunit core region was expressed by inducing with the OD_{600 nm} value 0.8, isopropylthiogalactoside (IPTG) 0.2 mmol/L at 37 ℃ for 9 h, and the molecular weight of the protein was about 50 kV. The cell of engineering bacteria pET-28a-α_c-BL21 was ultrasonically broken and centrifuged at low temperature. Target protein in the supernatant was purified with AKTA protein purification system using nickel ion affinity chromatography column.