According to the amino acids sequence of OC-IΔD86 gene and Escherichia coli codon usage, we synthesized this gene by overlap extension PCR method with 7 oligonucleotides DNA fragments. The PCR fragment was inserted into pGEM-T-easy vector and the recombined plasmid was named pGEM-T-OC-IΔD86. Two oligonucleotides into which the BamH I and Xho I sites were introduced were designed and synthesized based on pGEM-T-OC-IΔD86 and pet21b, and the PCR fragment into which the BamH I and Xho I sites were introduced was obtained. After digesting it with BamH I and Xho I, OC-IΔD86 gene was cloned into the corresponding sites of pet21b and obtained prokaryotic expression vector pet21b-OC-IΔD86. OC-IΔD86 gene was expressed in E. coli (BL21(DE3)plysS) after IPTG(Isopropyl β-D-1-thiogalactopyranoside) inducement for 5 hours. The fusion protein of OC-IΔD86:6His gene accounted for 11.4% of total protein and 16.4%of soluble protein, which had been successfully purified by Ni-NTA and concentrated by PEG20000. This protein can effectively inhibit papain activity in vitro and may be used in anti-nematode research in vivo.