Abstract: Objective 　To observe the depressive effect of celecoxib combined with cisplatin or X ray on A549 human lung adenocarcinoma cells. Methods 　The depressive effect on the proliferation of A549 cells was detected by MTS technique when celecoxib was conbined with cisplatin, the effect on SF of A549 cells was detected by MTS technique when celecoxib was combined with X ray, the apoptosis of A549 cells was detected by flow cytometry. Results 　Within a certain concent ration, celecoxib and cisplatin was able to inhibit the proliferation of A549 cells respectively, and dose2effect relationship was detected in the process. The combination of celecoxib (0. 35mg/ L) and cisplatin could enhance the depressive effect, and synergistic effect or addition effect was detected in the combination when the concent ration of cisplatin was more than 1mg/ L. In addition, celecoxib/ X ray (4 Gy) combination significantly decreased the SF of A549 cells and increased the apoptosis rate of A549 cells. Conclusion 　Celecoxib/ cisplatin combination could enhance the depressive effect on the proliferation of A549 human lung adenocarcinoma cells ; Celecoxib/ X ray could increase the apoptosis rate of A549 human lung adenocarcinoma cells, enhance the cells' radio sensitivity.