Objective:To study the effects of icotinib hydrochloride and 1α,25-dihydroxyxitamin D3 on proliferation and expression of EGFR of human lung adenocarcinoma cell line A549. Methods:The human lung adenocarcinoma A549 cell was cultured and treated by icotinib hydrochloride,1α,25-dihydroxyxitamin D3 and combination of these two medicines at different concentrations and time intervals. The CCK-8 assay was applied to analyze the proliferation inhibition rate. The expressions of EGFR total protein and EGFR mRNA were detected by western blotting and RT-PCR,respectively. Results:Compared with the single drug group,there was synergistic effect observed in the groups treated with icotinib hydrochloride and 1α,25-dihydroxyxitamin D3 along(P < 0.05). Compared with the control group and the group treated with icotinib hydrochloride alone,the expressions of EGFR total protein and EGFR mRNA of the group treated with 1α,25-dihydroxyxitamin D3 alone or the combination group were elevated dramatically(P < 0.05). Conclusion:There was synergistic effect in the cells treated with combination icotinib hydrochloride with 1α,25-dihydroxyxitamin D3. This may attribute to up-regulat of the expressions of EGFR mRNA and EGFR total protein by 1α,25-dihydroxyxitamin D3,and further to the anti-tumor effect of icotinib hydrochloride.