Abstract: Objective 　To const ruct and identify a novel expression vector harboring PNP gene. Methods 　Inserting PNP gene into pcDNA 3. 0, an expression vector containing PNP gene driven by the CMV promoter, pcDNA 3. 0/ PNP was const ructed by using recombinant DNA techniques. The recombinant was analyzed and identified by restriction enzyme, PCR and sequencing. The expression vector carrying PNP gene was transfected into three tumor cell lines by liposome-mediated method. The expressions of PNP gene in all cell lines were detected by RT-PCR method. Results 　The target fragment was cloned into the corresponding vector. The expressions of PNP gene in different tumor cell lines were positive. Conclusion 　The expression vector containing PNP gene under the control of a CMV promoter, is an novel effective expression vector for tumor gene therapy.