Abstract: Objective To explore the effects of Erlotinib combined with Celecoxib on apoptosis and expression of EGFR and COX-2 in lung cancer A549 cells.Methods A549 cells were observed under an inverted microscope ,MTT was used to measure the growth inhibitory effects of A549 cells by Erlotinib and Celecoxib．The cell apoptosis was studied byTUNEL and Hoechst33258 staining method . The cell cycle was detected by flow cytometer,and the expression of EGFR,COX-2 were determined by immunofluorescence. Results A great quantity of granules and vacuolus were observed in the combined treatment A549 ,with cell rounding and defluxion（P<0．05).The combination increased apoptosis of A549 (P<0．05) and significantly induced G1 phase arrest (P<0．05)and down-regulated expression of EGFR,COX-2 in A549 cells(P<0．05). Conclusions The results suggest that combination treatment with Erlotinib and Celecoxib showed significant synergistic inducing apoptosis and G1 phase arrest ，owing to down-regulating expressing both EGFR and COX-2．