OBJECTIVE To investigate the molecular mechanism underlying that dasatinib enhances the killing effect of gefitinib on HCC827 lung cancer cells. METHODS HCC827 cells and gefitinib-resistant HCC827GR cells were treated with 0, 100, 500, 1000 nmol/L gefitinib alone or in combination with 1000 nmol/L dasatinib. The proliferation of HCC827 cells and HCC827GR cells was detected by MTT assay, the activity of caspase 3 was tested by spectrophotometry, and the protein phosphorylation levels of Src and epidermal growth factor receptor (EGFR) were examined by Western blotting. RESULTS Src phosphorylation level was obviously enhanced in HCC827GR cells. Dasatinib significantly inhibited Src phosphorylation, promoted the cell proliferation and the expression of caspase 3. The combination of gefitinib and dasatinib had the stronger killing effect than gefitinib alone did. CONCLUSION The combination of dasatinib and gefitinib can enhance the inhibition on the expression of Src protein and the killing effect of gefitinib on HCC827 lung cancer cells.