OBJECTIVE: To knock down the expression of polymerase beta gene in human bronchial epithelial cells with technology of vector-mediated RNA interference (RNAi), to provide research tool for the study on the functions and mechanisms of polymerase beta in repairing of DNA damaged by environmental chemical pollutants (ECPs). METHODS: Technology of molecular clone was used to construct the recombination vector of "pEGFP-C1-U6-dsRNA" for the polymerase beta RNAi. The recombinants were transfected into human bronchial epithelial cells with kit of liperfectamine 2000. The control groups included normal human bronchial epithelial cells and human bronchial epithelial cells transfected with "pEGFP-Cl1. Cells were screened by G418, then technology of fluorescence microscopy imaging was used to observe the result of transrfection. The expresison level of polymerase beta was detected by Western blotting. RESULTS: The expression level of polymerase beta in human bronchial epithelial cells transfected with the recombinant of "pEGFP-C1-U6-dsRNA" was about 17.3% of what in the normal cells. CONCLUSION: The RNAi of polymerase beta gene in human bronchial epithelial cells was successful.