Objective Midazolam is one of the most commonly used anesthetics in operating room and intensive care unit. However, the effects of midazolam on AD neuropathogenesis have not been well determined. Here, we set out to assess the effects of midazolam on Tau hyperphosphorylation and expression of apoptosis protein in beta-amyloid peptideSUB>25-35/SUB>(AβSUB> 25-35/SUB>) treated PC12 cells. Methods The pheochromocytoma cells(PC12) were randomly allocated into four groups: control group(C); 10 μmol/L Aβ SUB>25-35/SUB> (A); 20μmol/L midazolam (M); Aβ SUB>25-35/SUB> and midazolam (MA), above all groups were incubated for 6 hours. The cell viability was determined by MTT assay，Western blotting and immunocytochemical stain were performed to observe the protein expression of Bcl-2 family and Tau phosphorylation at different sites. Results Incubating PC12 cells with midazolam at different concentration with Aβ SUB>25-35/SUB> can decrease the number of living cells in a dose-dependent way. The level of Tau protein phosphorylation in the sites of Ser396 and Ser404 increased in MA group compared with A group (EM>P/EM><0.05)，and the Bax level of MA group significantly higher than A grou