Abstract: To further evaluate the effect of miR-217 in the proliferation of mouse adult pancreatic stem cells, we firstly transfected adult pancreatic stem cells with miR-217 mimics and studied the effect of miR-217 on proliferation through Western blot and immunofluorescence. Results showed that during the proliferation of adult pancreatic stem cells, miR-217 inhibited the protein expression of Ki-67 and Cyclin D1, which are related to cell propagation. As well as that, to investigate the target genes of miR-217 and their conserved sites bound by the seed region of miR-217, we used bioinformatic algorithms to find a potential target of miR-217 and verified by dual-luciferase activity assay. Surprisingly, dual-luciferase activity assay revealed that miR-217 could decrease PMIR-REPORT-Sirt1-3′UTR luciferase activity and Sirt1 is a direct target of miR-217. Finally, we verified the function of Sirt1 in the proliferation of pancreatic stem cells. Overexpression of miR-217 in pancreatic stem cells inhibited the level of Sirt1 in protein level but not in mRNA level. Furthermore, activator of Sirt1 played positive effect on colony formation ability and cell proliferation and inhibitor of Sirt1 showed the opposite function. In conclusion, miR-217 inhibits the proliferation of mouse adult pancreatic stem cells through Sirt1 and decreased expression of miR-217 to contribute to the pancreatic stem cells development.