Objective To study the role of capsaicin on improving the sensitivity of cholangiocarcinoma (CCA) cells to 5 fluorouracil(5-FU)and to investigate its molecular mechanism.Methods The MTT and animal experiment were performed to study the effect of capsaicin on the sensitivity of CCA cells to 5-FU,and the q-PCR and Western blot were performed to study its molecular mechanism.Results The effect of 5-FU inhibiting the growth of CCA cells and in vivo was significantly enhanced by capsaicin (60 μmol/L),as well as the apoptosis induced by 5-FU (P ＜ 0.01).In molecular mechanism study,capsaicin down-regulated the expression of beclinl and atg5,but inhibited the 5-FU-induced autophagy of CCA cells.In addition,capsaicin effectively increased the phosphorylation levels of S6 (S235/236) and AKT (S473).Conclusions Capsaicin can promote cell apopto sis and inhibit cell autophagy to improve the sensitivity of CCA cells to 5-FU significantly,which maybe associated with the activation of PI3K/AKT/mTOR pathway in CCA cells.