Objective To investigate the effect of amyloid-β protein 1-42 (Aβ1~42)on the proliferation of neural stem cells (NSCs).Methods The NSCs of newborn mice were cultured in vitro,and treated with 0.5,0.1 and 0.02 μmol/L Aβ1~42,respectively,at the same time,a solvent control and positive drug control were set up to observe neurospheres.MTT assay was used to determine viability of NSCs,and immunocytochemical staining of characteristic protein and BrdU labeling were performed to identify NSCs and their proliferative properties.Results A great deal of neurospheres were formed in the 0.1 μmol/L group of Aβ1~42,differentiating from that in control group (P≤0.01),in which their characteristic proteins(nestin)of NSCs and BrdU labeling were positive through immunocytochemical stainings.Conclusions The low concentration of Aβ1~42 (0.1 μmol/L)can promote the proliferation and fission of NSCs in vitro.