Objective To observe the effect of transplantation of embryonic stem cell(ES) on neurological functional recovery of injured spinal cord in adult mouse. Methods The ES cells were cultured and induced in vitro. Fifty C57/BL6J mice were made animal model of semicut mice of T9，10. The ES cellderived neural precursors cells were transplanted into the vertebral canalaround injured spinal cord semi-cut mice. Twenty-eight C57/BL6J mice were randomly divided into three groups: sham operation group(group A,n=9), operation／cell group (group B，n=10), and operation／DMEM group(group C,n=9). RT-PCR analysis, X-gal staining and immunofluorescence were used to observe the cells survival and differentiation in the spinal crod. BBB test was performed to study functional improvement. Results ES cells induced and cultured in vitro displayed clonal growth with circle or ovoid shape and had one or more nucleoli. RT-PCR result showed that the induced ES cells expressed mRNA of Nestin and microtubuleassociated protein, but did not express glial fibrillory acidic protein(GFAP). There was statistically significant difference in BBB scoring between group A and groups B, C after operation (P＜0.01). There was statistically significant difference in BBB scoring at 1, 2 and 4 weeks of operation(P＜0.01), but no statistically significant difference at 6 and 8 weeks of operation between groups B and C(P＞0.05). The X-gal staining results werepositive in group B and negative in groups A and C. The immunoflurescence resultshowed neurofilament green fluor and no expression of GFAP in injured spinal cord region. Conclusion After transplantation, ES cellderived cells can survive, transfer into the injury position, and differentiate into neurons, but spinal cord function has no obvious improvement.