To explore the neuroprotective effect of magnesium sulfate on the apoptosis of neural stem cells induced by radiation, neural stem cells were obtained from newborn sprague-dawley rats cerebral hemisphere, and the identification of neural stem cell was done by immunofluorescence after culturing for 24 h. Neural stem cells were cultured by different concentrations of magnesium sulfate and the right concentration of magnesium sulfate was chosen to be 0.00125 mg/mL. In the experiment the neural stem cells were randomly divided into 3 groups: blank control group, experimental control group (radiation) and experimental group (radiation and treated with magnesium sulfate). The whole neural stem cells of experimental control group and experimental group were irradiated by a dose of 2 Gy or 4 Gy with γ-rays. The apoptosis were detected at different time after irradiation in the range of 24 h, 48 h, and 72 h, respectively. The CCK-8 and the morphology of neural stem cells were observed by TEM. Compared with blank control group, the apoptosis rate of experimental control group significantly increased (t（2Gy、72h）=30.60, t(4Gy、72h)=31.85, p<0.05). Compared with control group, the apoptosis rate of experimental group significantly decreased(t（2Gy、72h）=9.08,t（4Gy，72h）p<0.05). Accordingly, magnesium sulfate can decrease apoptosis rate and reduce the injury of neural stem cells in the early stage after irradiation.Cited