Objective To investigate the expression and role of roundabout guidance receptor 1 (Robo1) in the neuronal differentiation of neural stem cells (NSCs) induced by valproate (VPA).   Methods The hippocampus NSCs of SD rats were isolated and cultured. Normal NSCs and VPA-treated NSCs were extracted from 10 SD rats. After VPA treatment, the proportion of neuron-specific marker β-tubulin Ⅲ (Tuj1) positive neurons differentiated from NSCs were detected by immunofluorescence. The differentially expressed mRNA in normal NSCs and VPA-induced NSCs were detected by gene chip technology. After VPA treatment, the expression levels of Robo1 mRNA and protein were detected by Real-time PCR and Western blotting. The dynamic changes of Robo1 mRNA were detected by Real-time PCR after the differentiation of NSCs. After the expression of Robo1 was down-regulated in NSCs by small interfering RNA, the expression of Robo1 protein was detected by Western blotting, and the expression levels of neuron-specific markers Tuj1 and microtubule associated protein-2 (MAP-2) were detected by Real-time PCR and immunofluorescence.   Results VPA induced NSCs to differentiate into neurons. Compared with the control group, the expression levels of Robo1 mRNA and protein in the differentiation of NSCs were significantly up-regulated during valproate treatment. After interference of Robo1 expression, not only Robo1 upregulation was inhibited during the differentiation of NSCs induced by VPA, but also the proportion of NSCs differentiated into neurons decreased.   Conclusion VPA may promote the differentiation of NSCs into neurons by up-regulating the expression of Robo1.