Objective:To investigate the effect of β-elemene on mitochondrial structure and function of the A549 cells of non-small cell lung cancer(NSCLC),and to elucidate the mechanism of β-elemene in the treatment of NSCLC.Methods:The A549 cells at logarithmic growth stage were divided into blank control group(0 mng·L-1 β-elemene),low,medium and high doses of β-elemene groups(10,25 and 50 mg·L-1),and solvent control group(0.5％ethanol in equal volume).After treatment for 24 h,the cell activities in various groups were detected by MTT assay;the morphology changes of mitochondria in the cells in various groups was observed by transmission electron microscope;the levels of adenosine 5′-triphosphate(ATP)in the cells in various groups were detected by colorimetry;the mitochondrial membrane potential of the A549 cells in various groups were detected by JC-1 flow cytometry;mitochondrial membrane permeability transfer hole assay was used to detect the mitochondrial membrane permeabilities of the cells in various groups.Results:The MTT results showed that compared with blank control group,the cell activities in low,medium and high doses of β-elemene groups were decreased gradually(P＜0.05),while the cell activity in solvent control group had no significant change,and the difference was not significant(P＞0.05).The transmission electron microscope results showed that compared with blank control group,the mitochondria of A549 cells in low,medium and high doses ofβ-elemene groups showed swelling,vacuolation,disordered arrangement and dissolution,while the mitochondrial morphology of the A549 cells in solvent control group had no significant changes.The colorimetric method results showed that compared with blank control group,the ATP levels in the A549 cells in low,medium and high dose β-elemene groups were gradually decreased(P＜0.05),while the ATP level in the A549 cells in solvent control group had no significant change,and the difference was not significant(P＞0.05).The JC-1 flow cytometry method results showed that compared with blank control group,the mitochondrial membrane potential of the A549 cells in low,medium and high doses ofβ-elemene groups were decreased,and the percentages of the cells in Q2-4 region were increased(P＜0.05);the percentage of the A549 cells in the Q2-4 region in solvent control group had no significant change.The results of mitochondrial membrane permeability transfer hole experiment showed that compared with blank control group,the mitochondrial membrane permeabilities of the A549 cells in low,medium and high doses of β-elemene groups were increased,and the percentages of the cells in M4 region were increased(P＜0.05);the mitochondrial membrane permeability of the A549 cells and the percentage of the M4 cells in solvent control group had no significant changes,and the difference was not significant(P＞0.05).Conclusion:β-elemene can inhibit the proliferation of the A549 cells,and the mechanism may be that the mitochondrial structure of A549 cells is damaged by reducing the level of ATP and mitochondrial membrane potential,changing the mitochondrial morphology and increasing the mitochondrial membrane permeability.