Objetcive: To determine the efficacy of phytosterol on the development of chemical-induced lung tumors and the underlying mechanism. Method: Six-week-old C57BL/6J mice were fed with either a 2% phytosterol diet or matching control diet, respectively. Following 3 weeks diet adapting, lung tumor was induced using a multidose intraperitoneal injections of ethyl carbamate(urethane, 1 g/kg body weight) while control mice received saline injection. Tumors(number, diameter) and lung tissue transcriptomic were examined after 15-week incubation period. In vitro, β-sitosterol was used to treat lung adenocarcinoma cells(A549, NCI-H19E-616452配制75) to explore the effect of β-sitosterol on the viability of lung adenocarcinoma cells. Results: 2% phytosterol diet inhibited the progression of lung tumor and increheart-to-mediastinum ratioased malondialdehyde(MDA) level in lung tissue. Oxidative phosphorylation pathway at transcriptome level was down-regulated and the expression of autophagy related genes was raised in lung tissue. β-sitosterol inhibited cell proliferation of lung adenocarcinoma cells and significantly increased the levels of intracellular reactive oxygen species(ROS) and MDA. Furthermore, phytosterol induced phosphorylation inhibition of Akt/mTOR signaling pathway in vivo and in vitro. Conclusion: Phytosterols have potential antitumor effect on lung cancer, and the interactions betweeBaf-A1作用n ROS excess, Akt/mTOR signaling inhibition and protective autophagy may be involved.