目的　构建能表达抗胃癌单链抗体免疫毒素的重组质粒并进行表达。方法　应用基因工程方法 ,将抗胃癌的单链抗体基因与绿脓杆菌外毒素基因进行重组 ,得到的重组质粒转化大肠杆菌BL - 2 1,鉴定后的阳性克隆经IPTG诱导表达。结果　重组质粒经酶切鉴定正确 ,IPTG诱导后可看到明显的表达带 ,分子大小与预计值相符。结论　得到了能表达抗胃癌单链抗体免疫毒素的重组质粒。 Objective To construct and express recombinant plasmid expressing anti-gastric cancer single chain antibody immunotoxin. METHODS: The genetic engineering method was used to recombine single-chain Fv antibody against gastric cancer and Pseudomonas exotoxin gene. The resulting recombinant plasmid was transformed into E. coli BL-21. The identified positive clone was induced by IPTG. Results Recombinant plasmids were correctly identified by enzyme digestion. After IPTG induction, obvious expression bands were observed. The molecular size was consistent with the predicted values. Conclusion The recombinant plasmid expressing anti-gastric cancer single chain antibody immunotoxin was obtained.