Objective To extract and purify the cytoplasmic neurotrophic proteins from bone marrow stromal cell and to test their neurotrophic activity. Methods Bone marrow stromal cells were collected from rat femur,after ultrasonicgrind and ultracentrifugation, the supernate was ultrafiltrated and concentrated,the proteins that molecular weight was greater than 10 ku were collected. The neurotrophic active substance was extracted and purified by Sephadex G-100 gel chromatography and high performance liquid chromatography (HPLC). Then their neurotrophic activity was tested in cultured spinal cord motoneuron with MTT method and morphous observation. Results After supernate was analyzed by Sephadex G-100 chromatography, peak Ⅱ could promote the growth of neuron. A further analysisof Peak II with HPLC showed that peak A could promote the growth of neuron. The SDS-PAGE analysis of peak A indicated that a main protein zone with molecular weight of 13 ku was obtained. Conclusion The protein of 13 ku in MSCs has neurotrophic activity.