Objective To observe the effect of aspirin on the proliferation inhibition and apoptosis of human adrenal cortical cancer cells, and to explore preliminarily the related mechanisms. Methods The human adrenal cortical cancer cells were cultured in vitro. The experimental group was DEME/F-12 complete medium which contained different concentrations of aspirin (final concentration of 0.125, 0.25, 0.5, 1 mg/ml). The control group was DEME/F-12 complete medium which had no aspirin but 1%anhydrous ethanol instead. After treatment by aspirin at different concentrations for different durations (24, 48, 72 hours), we detected the proliferation inhibition of SW-13 cells and H295R cells by methyl thiazolyl tetrazolium (MTT) method, observed the changes of cell morphology with the inverted microscope; Observed and counted apoptotic cells through Hoechst33258 fluorescent staining, tested the cell apoptosis by flow cytometry, and detected the expression of Bcl-2 and Bax by western blotting. Results The date of MTT showed that after treated by different concentrations of aspirin,the growth inhibition ratio of SW-13 cells and H295R cells were higher than the control group (P＜0.05), and at the same time, the inhibition ratio would increase when the drug concentration increased ( P＜0. 05 ), with a dose-dependent tendency. When the drug concentration was constant, the inhibition ratio increased with the duration of the drug (P＜0.05), which showed a time-dependent tendency. The number of apoptosis cells and the cell apoptosis rate of both SW-13 and H295R which were treated by different concentrations of aspirin for 48 hours were higher than the control group ( P＜0. 01). According to the analysis of grayscale value of western blotting, Aspirin can increase the expression of Bax ( P＜0.05). On the contrary, the expression of bcl-2 in the experimental group was lower than that in the control group (P＜0.05). Conclusion Aspirin may inhibit the growth of human adrenal cortical cancer cell in vitro and induce its apoptosis, and the possible mechanism may be correlated with the up-regulation of the expression of Bax, and down regulation of Bcl-2 expression.