Objective To discuss whether Bmi-1 is participated in maintenance of the self-renewal and proliferation of neural stem cells (NSCs) isolated from fetal striatum. Methods Neural stem cells were transfected with Bmi-1 targeted shRNA-lentiviral vectors and GFP control vector respectively. At 0 hour,48 hours, 72 hours, and 168 hours after transfection, the Bmi-1 mRNA expression level was measured by Realtime PCR. The numbers and diameters of newly formed neurosphere were calculated under microscope. Results The transfection efficiency was shown to be more than 90% by expression of reporter gene GFP. At 0 hour,48 hours, 72 hours and 168 hours after transfection, transcription level of Bmi-1 were to be （107.3±8.0618）%, （32.7±9.74）%, （24.4±12.15）%, （32.7±10.39）% compared with 0 hour, the relative expression levels of Bmi-1 at 48 hours, 72 hours, and 168 hours were significantly decreased(EM>P/EM><0.05). Accordingly, The number and size of newly formed neurospheres were als