【Abstract】 Objective To investigate the effects of different concentrations of capsaicin on the proliferation and apoptosis of A549 cells after hypoxia/reoxygenation.Methods A549 cells were randomly divided into normal control group (control group), hypoxia 36h and reoxygenation 24h group (HR), cap0.25+HR group, cap25+HR group, cap25+HR group, cap25+HR group and cap2500+HR group. In addition to the control group, A549 cells in each group were cultured in incubators with 1% O2, 5% CO2 and 94% N2 for 36 h. Then the cells were incubated in 5% CO2 incubator for 24 hours. The capsaicin treatment groups were treated with various concentrations capsaicin before hypoxia. After the end of reoxygenation, cell viability was measured by cell counting kit8. The cells of control group, HR group,cap25+HR group and cap250+HR group were collected and stained with AnnexinVFITC/PI and detected the apoptotic rate with flow cytometry.Results +9-*Compared with group HR, the proliferation activity in low dose of capsaicin (2.5μM, 25μM and 250μM) groups increased (P＜0.05), but it decreased in high concentration (2500μM) treatment group (P＜0.05). Compared with HR group, the apoptosis rate in cap25+HR and cap250+HR groups significantly decreased (P＜0.05) and the protective effect is more obvious in high concentration group(250μM). Conclusion Capsaicin can increase the proliferation of A549 cells and inhibit the apoptosis.