Abstract: Objective To investigate the effect of Hinokitiol combined with chloroquine on the apoptosis of human lung adenocarcinoma cell line H1975. Methods Human lung adenocarcinoma cell line H1975 was chosen. The viability of H1975 cells treated with Hinokitiol and(or) chloroquine were determined by MTT. The expression of apoptosis-related proteins, Cleaved PARP, Cleaved Caspase-3 and Bax, were detected by Western blot. Results After treated with 2.5, 5, 10μmol/L Hinokitiol for 24h, the viability of H1975 cells was significantly decreased in a dose-dependent manner, moreover, the apoptosis-related proteins, Cleaved PARP, Cleaved Caspase-3 and Bax, were upregulated by hinokitiol. The viability of H1975 cells treated with hinokitiol and chloroquine was significantly decreased, in addition, the apoptosis-related proteins, Cleaved PAR and Caspase-3, were increased, compared with Hinokitiol alone group. Conclusion Chloroquine increased Hinokitiol-induced apoptosis of H1975 cells.