The human GM CSF cDNAandEGFP cDNA were linked together with IRES and then inserted into the expression vector pCI Egr 1, which was constructed by substituting CMV promoter in pCIneo with the Egr 1 promoter(Egr EG).The vector was transfered into human bone marrow stromal cell line HFCL by Lipofectin TM . The results indicated that the activity of EGFP in transfected cells increased at 18h after exposure to 2.5 Gy. The amounts of secreted GM CSF and CFU GM in serum free supernatants of Egr EG was significantly higher than the control group. EGFP and GM CSF cDNA were successfully integrated and expressed in the cells, which were confirmed by FACS and RT PCR analysis respectively. These in vitro data provide an experimental basis for the in vivo use of gene therapy of GM CSF gene regulated by Egr 1 promoter to protect hematopoiesis from total body irradiation.