Abstract: objective To study the effect of nerve growth factor（NGF） on secretion of Th1/Th2 cytokines. Methods (1)32 SD rats were divided into 4 groups randomly: asthma（the asthmatic models were established）, control, NGF, anti-NGF-antibody groups. After 14 days the lung tissues were detected the pathologic changes by HE staining. NGF in the lungs were determined by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry assay。The levels of interferon-γ(IFN-γ, one of the Th1 cytokines) and interleukin-4 (IL-4, one of the Th2 cytokines) were detected by ELISA. Results In the asthma group, more inflammatory cells were detected in the lungs. more NGF-immunoreactive infiltrating cells and higher levels of NGF（P<0.001） in the lungs were detected. The levels of IL-4 （P<0.05）were enhanced and the levels of IFN-γ（p<0.001）were decreased significantly in the lungs. In the lungs of the asthma group, the significant negative correlation was found between NGF and the ratio of IFN-γand IL-4（P<0.01）. In the NGF group, the changes were enhanced significantly than those in the asthma group. on the contrary, in the the anti-NGF-antibody group, the changes were decreased significantly than those in the asthma group. Conclusion In addition to inducing neurogenic inflammation in asthmatic rats, NGF may contribute to promote amplify Th1/Th2 cells immune imbalance in asthma by enhancing Th2 cytokines and decreasing Th1 cytokines.