To observe the effects of miR-125b on the differentiation of rat bone marrow mesenchymal stem cells (BMSCs) into neuron-like cells, rat BMSCs were isolated and transfected with Syn-rno-miR-125b* miScript miRNA Mimic (Mimic + BME group), with anti-rno-miR-125b* miScript miRNA Inhibitor (Inhibitor + BME group) and BME control was set up without transfection. Blank controls without transfection and induction by BME was also set up. BMSCs of three groups including Mimic + BME group, Inhibitor + BME group and BME group were induced to differentiate into neuron-like cells by β-mercaptoethanol (BME). Cells in the Blank group were not treated by BME. mRNA expression of miR-125b was determined with qRT-PCR in each group. mRNA and protein expressions of seven nerve cell markers, including β3 tubulin, neural microtubule-associated protein (MAP-2), neurofilament protein (NF), neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), Nestin and Vimentin in the four groups were determined by RT-PCR and Western blots. GFAP and Nestin were detected by immunofluorescent and immunocytochemistry assays. Compared with BME group, mRNA and protein expression of β3 tubulin, MAP-2, NF, NSE, GFAP, Nestin were significantly increased in the Mimic + BME group (P < 0.01), but significantly decreased in the Inhibitor + BME group (P < 0.01). Cells in the Mimic + BME group were more like nerve cells in morphology than cells in the BME groups. Thus miR-125b can promote BME to induce rat BMSCs differentiation into neuron-like cells.