Objective:To in vestigate the method of culturing neural stem cell s(NSCs) in vitro and measurement of n6/n3 ratios and DHA contents in these NSCs cultured from subventricular zone in adult mice. Methods：Subventricular zone was isolated from the brains of 8～10 weeks old C57BL/6 mice, and the NSCs were cultured in floating in vitro. Some marker genes of NSCs and differentiated cells were detected by immunofluorescendce; polyunsaturated fatty acids and n6/n3 ratios were measured by gas chromatography. Results：NSCs proliferated continuously in vitro, most cells were Nestin positive. NeuN，TuJ1，GFAP and O4 positive cells were detected by immunofluorescence in differentiated neural cells. Polyunsaturated fatty acids were richer in NSCs. Conclusion：NSCs cultured from subventricular zone in adult mice have proliferation and self-renewal abilities. n3 polyunsaturated fatty acids and DHA in NSCs are significantly higher than those in tails.