〔Abstract〕 Objective To study the effect of bufalin on the proliferation and apoptosis of human colorectal cancer cell line HCT116, and to explore the role of endoplasmic reticulum stress(ERS) in this process. Methods The effect of bufalin on the proliferation of HCT116 cells was determined by CCK-8 assay. After HCT116 cells were treated with different concentrations of bufalin for 48 hours, cell apoptosis was detected by Annexin V/PI assay, and the expression of apoptosis-related proteins Bax and Bcl-2 was detected by Western blot. At the same time, the expression of ERS-related proteins glucose regulated protein 78(GRP78), phosphorylated protein kinase R like endoplasmic reticulum kinase(p-PERK), eukaryotic translation initiation factor 2α(eIF2α), phosphorylated eukaryotic translation initiation factor 2α(p-eIF2α) and C/EBP homologous protein(CHOP) was detected by Western blot. HCT116 cells were divided into control group, bufalin group and combination group(bufalin+4-phenylbutyric acid), and the expression of apoptosis-related proteins Bax and Bcl-2 was observed by Western blot. Results CCK-8 assay showed that bufalin could inhibit the proliferation of HCT116 cells. Apoptosis assay showed that bufalin could induce apoptosis of HCT116 cells. The results of Western blot showed that bufalin could up-regulate the expression of pro-apoptotic protein Bax and down-regulate the expression of anti-apoptotic protein Bcl-2. It could also induce ERS and activate PERK/eIF2α/CHOP pathway. When bufalin combined with 4-phenylbutyric acid, the apoptosis-promoting effect of bufalin was inhibited. Conclusion Bufalin can effectively inhibit the proliferative activity and induce apoptosis of HCT116, which is achieved to some extent by activating ERS.