Abstract: Objective To investigate the role of human umbilical cord mesenchymal stem cell-derived exosomes （hUC-MSC-Exo） in the tunicamycin-induced apoptosis of renal tubular epithelial cells （HKC）. Methods Endoplasmic reticulum stress （ERS） was induced by tunicamycin in HKC cells. Cell proliferation was detected by CCK-8 assay. The expression levels of ERS-related proteins of glucose-regulated protein 78 （GRP78）,GRP94 and C/EBP homologous protein （CHOP） were determined by Western blot. Cell apoptosis was assessed by flow cytometry. hUC-MSC-Exo were isolated and identified by flow cytometry. The effects of different concentrations of hUC-MSC-Exo （0,40,60,80,100,150 and 200 μg/mL） upon cell activity were evaluated. Cell proliferation and apoptosis after co-treatment with hUC-MSC-Exo and tunicamycin were assessed by resazurin assay and flow cytometry. Results Treatment with 1,2 and 4 μg/mL tunicamycin could inhibit the proliferation of HKC in a concentration-dependent manner. Different concentrations of tunicamycin could induce ERS and cell apoptosis in HKC. Treatment with 100,150 and 200 μg/mL hUC-MSC-Exo could enhance cell proliferation. Compared with the 2 μg/mL tunicamycin group,cell proliferation was significantly increased in the 2 μg/mL tunicamycin and 150 μg/mL hUC-MSC-Exo co-treatment group （P < 0.05）. The apoptosis rate in the 2 μg/mL tunicamycin group was （14.16±1.58）%,and （8.18±0.58）% in the 2 μg/mL tunicamycin and 150 μg/mL hUC-MSC-Exo co-treatment group,and the difference was statistically significant （P<0.05）. Conclusion hUC-MSC-Exo can significantly alleviate HKC apoptosis induced by ERS.