Abstract: Objective To observe the proliferation characteristics of NIH3T3 cell line under expression of different type DNA polymerase B(DNA poBl).Methods The wild pol β and deletemutational pol β of esophageal cancer cellswere transfected into NIH3T3 cell line by lipofectamine method.The stable expression pol β NIH3T3 line was constructed.The location of pol β gene-encoded protein was observed with fluo rescent microscope.The growth curve was drawn with MTT method and the cell cycle was examined with flow cytomete.rResults It was proved that two pol β genes were transfected into the NIH3T3 cell line successfully.The location of wild type pol β prote in was mostly inside the nuclear,but the delete mutational pol β prote n was distributed in the whole cell.The growspeed of NIH3T3-wild type(wt)pol β was not obviously different compared with control cells and NIH3T3-EGFP(P>0.05).But the grow speed of NIH3T3-delete mutational type (dmt)tpol β was faster obviously(P<0.05).Furthermore,the cell account of Speriod of NIH3T3-dmtpol β was obviously increased(P<0.05),but that of NIH3T3-wt pol β showed no obvious change(P>0.05).Conclusion Expression of exogenous wild pol β is no obvious effect on the proliferation of NIH3T 3 cell and the expression of exogenous delete mutational po β can make NIH3T3 cells proliferate.There sult has great significance to further dicuss the pathogenesis of esophageal cancer and provides a strong basis for esophageal cancer biotherapy.