HCV NS3 protein plays an important role in the carcinogenesis of HCV related HCC. But the mechanism remains to be determined. The cell lines and transgenic mice used in previous studies were rarely based on HCV natural infection process, so the results acquired may need to be further evaluated. Under such background, the eukaryotic plasmid expressing HCV NS3 protein (pcDNA3.1/NS3 ) was constructed. Through transfecting the human hepatocyte line QSG7701 with pcDNA3.1/NS3, the research system expressing HCV NS3 protein was constructed successfully. On this basis, the effects of HCV NS3 on cell proliferation, the phosphorylation of MAP kinases and activity of transcription factors AP-1, NF-κB and STAT3 were investigated. The results showed that HCV NS3 protein could enhance proliferation, up-regulate phosphorylation of Erks and the activity of transcription factors AP-1, NF-κB and STAT3 in human hepatocytes. It is speculated that, HCV NS3 protein up-regulates ERKs/AP-1 activities is an important mechanism by which HCV NS3 protein enhances cell proliferation, its up-regulation of activity of transcription factors NF-κB and STAT3 might be relevant to the acute hepatitis associated with HCV infection.