Abstract: Objective To investigate the effects of HER2 shRNA on the chemotherapy sensitivity of Mice Lewis cells. Methods pGPU6/RFP/Neo-erbB-2 and pGPU6/RFP/Neo-shNC plasmids were synthesized and transfected into mice Lewis cells by Lipofectamine 2000.The levels of HER2 mRNA and protein were tested by RT-PCR and Western blot, respectively.The apoptotic rates of cells in non-transfected group, pGPU6/RFP/Neo-shNC group,pGPU6/RFP/Neo-erbB-2 group,Carboplatin group, pGPU6/RFP/Neo-shNC plus Carboplatin group and pGPU6/RFP/Neo-erbB-2 plus Carboplatin group were tested by FCM. Results The levels of HER2 mRNA and protein in pGPU6/RFP/Neo-erbB-2 group were lower than those in pGPU6/RFP/Neo-shNC group and non-transfected group.The apoptotic rate of cells in pGPU6/RFP/Neo-erbB-2 plus carboplatin group was higher than those in other groups (all P＜0.01). Conclusion HER2 shRNA could increase the sensitivity of mouse Lewis cells to carboplatin.