Objective To investigate the effect of extracellular signal-regulated kinases(ERK) signal transduction in the process of NSCs differentiating into neurons in the fimbria-transected hippocampi’s extracts. Methods Twelve Sprague-Dawley rats’right fimbrias were transected. The extracts were gained from the fimbria-transected hippocampi at the 14th day normal rat, and the extracts supernatant fluid was collected after centrifugal process, then the protein concentration in the extracts was determined. In the serum-free medium，NSCs from the fetal hippocampus were planted on 24 well culture plate, then were divided into three group and eight wells for each group as follows: the transected group contained the extracts of the fimbria-transected hippocampi; the normal group contained the extracts of the normal hippocampi; the pure control group have no extracts. After cultured for 14 days,the cells were detected by using MAP-2 and p-ERK immunofluorescence. Result The number, area, perimeter of MAP-2 positive neurons were all declined in transected group, the normal group and the control group orderly. Statistic results showed significant difference between every two groups. The number of MAP-2/p-ERK double-positive neurons were decreased in transected group, the normal group and the control group orderly, but the percentage of double-labeled neurons in total MAP-2 positive neurons were increased in turn. In these two aspect, there were also significant difference between every two group. And most of the MAP-2/p-ERK double-positive neurons were immature. Conclusion The extracts of the fimbria-transected hippocampi had obvious effects on promoting NSCs differentiating into neurons and speeding up the maturation of neurons than those of the normal hippocampi. The morphological results showed that ERK signal transduction might be related to the differentiation of NSCs i