Objective:To construct the recombinant eukaryotic expression vector pcDNA3.1(+)/hFasL and investigate its transfection and transient expression in COS-7 cells.Methods:The full-length cDNA of hFasL was obtained from the plasmid vector pBluescript II KS(+)/hFasL cut with Xba I and then subcloned into eukaryotic expression vector pcDNA3.1(+).The recombinant plasmid pcDNA3.1(+)/hFasL was identified with restriction enzyme digestion and sequence analysis.It was then transfected into the COS-7 cells by Lipofectin Reagent and its expression was determined by immunocytochemical staining.Results:Restriction enzyme digestion analysis with XbaⅠ?DraⅡ?HindⅢ and DNA sequencing indicated the correct construction of the recombinant plasmid;Immunocytochemical staining showed the expession of hFasL on COS-7 cells.Conclusion:The construction and expression of the eukaryotic expression plasmid pcDNA3.1(+)/hFasL have been achieved successfully.