Objective To study the effect of gypenosides (GPs) on proliferation of neural precursor cells (NPCs) in vitro. Methods NPCs were isolated from the brains of embryonic rats on day14 of pregnancy. After adherent culture for 7 days, the cells were passaged for the first time, and cultured for another 3 days. We identified the purity of the NPCs by immunofluorescence technique, then incubated the NPCs together with GPs in different concentrations(0, 25, 50, 100, 200 and 400μg／mL)for 48 hours. After that the purity of the NPCs was again identified, activity was measured by MTT chromatometry, a cell growth curve was drawn by cell counting, the proliferation of NPCs was measured by bromodeoxyuridine (BrdU) incorporation, and determined the expression level of proliferating cell nuclear antigen (PCNA) was determined by Western blot. Results The purity of the NPCs cultured for 3 days after being passaged for the first time was 97 ％. Without changing the purity of NPCs, GPs increased the activity of NPCs, accelerated the growth of NPCs, improved the positivity rate of BrdU, and up-regulated the expression level of PCNA. Conclusion GPs promote the proliferation of NPCs in vitro through increasing the expression level of PCNA, and the optimal concentration of GPs is 100μg／mL.