【Abstract】 Objective To investigate the effects of salvianolic acid B on oxidative stressinduced apoptosis and autophagy of thyroid cancer cells. Methods Different doses of salvianolic acid B were used to treat TPC-1 and thyroid follicular epithelial Nthy-ori 3-1 cells of thyroid cancer. Cell viability was detected by CCK8 after 24 hours. Doses with no significant toxicity (2.5, 5, 10 μg/mL) were selected for followup in experiments. The flow cytometry was used to detect intracellular ROS levels and apoptosis. Western blot was used to detect intracellular and mitochondrial cytochrome C and expression levels of apoptosis and autophagyrelated proteins. The immunofluorescence was used to detect LC3 levels. In addition, after adding the compound AMPK inhibitor compound C (50 nM) to the cells, the cells were randomly divided into control group, salvianolic acid B 10 μg /mL group, compound C group, compound C+salvianolic acid B 10μg/mL In the ml group. The intracellular ROS level and apoptosis were detected by flow cytometry. The expression of AMPKrelated proteins and autophagyrelated proteins were detected by Western blot. Results The survival rate of TPC-1 and Nthy-ori 3-1 cells was reduced in a salvianolic acid Bdependent manner. When salvianolic acid B concentration exceeded 20 μg/mL, the survival rate of TPC-1 cells was significantly reduced (P＜0.05). When the salvianolic acid B concentration exceeded 40 μg/mL, the survival rate of Nthy-ori 3-1 cells was significantly reduced (P＜0.05). Compared with the control group, ROS level, apoptosis rate, Bax, Cleaved caspase 3, Beclin1 and Cyto C protein expression level, LC3 level, AMPK phosphorylation level and LC3-II/LC3-I ratio in TPC-1 cells were significantly increased after 5 and 10 μg/mL saldanolic acid B pretreatment (P＜0.05). Protein expression levels of Bcl-2, P62 and Cyto C in mitochondria were significantly decreased (P＜0.05). Compared with the control group, the phosphorylation level of AMPK, the ratio of LC3-II/LC3-I, the ROS level and the apoptosis rate were significantly increased in salanolic acid B 10 μg/mL group (P＜0.05). The phosphorylation level of AMPK, LC3-II/LC3-I ratio, ROS level and apoptosis rate were significantly reduced in Compound C group (P＜0.05). Compared with Compound C group, the phosphorylation level of AMPK, LC3-II/LC3-I ratio, ROS level and apoptosis rate were significantly increased in Compound C+salanolic acid B 10 μg/mL group (P＜0.05). Conclusion Salvianolic acid B promotes oxidative stressinduced apoptosis and autophagy of thyroid cancer cells through AMPK activation.