Objective To construct an eukaryotic expression vector of Hepatitis C virus(HCV) nonstructural protein NS4B, and investigate the effect of this protein on apoptosis of U2OS cells. Methods The fragment of target gene NS4B was obtained by PCR, and connected with the PCMV-tag2b vector using the homologous recombination method, and the PCMV-tag2b-NS4B was transformed into the DH5a. The right recombinant plasmid was selected. Lipofectamine 2000 was used to transfect PCMV-tag2b-NS4B into U2OS cells. Western blot was applied to detect the expression of HCV NS4B protein in U2OS cells, and immunofluorescence (IF) was used to assess the apoptosis of U2OS cells. Results The data showed that the recombinant plasmid PCMV-tag2b-NS4B was consistent with the one published on NCBI and could express HCV NS4B protein in U2OS cells. DAPI staining showed that the apoptosis rate of the PCMV-tag2b-NS4B group was (17.25 ±2.95)% and that of the control group was (6.53 ±2.36) %. Conclusions The eukaryotic expression vector of HCV NS4B has been successfully constructed, and HCV NS4B protein is expressed in U2OS cells and induces apoptosis.