Abstract: Objective To study the role of 5’ untranslated region (UTR) and intron in the expression of human thrombopoietin (TPO) gene. Methods A number of expression vectors containing TPO mini-gene fused to the regulatory elements of cytomegalovirus (CMV) were constructed and transfected via lipofectin into cultured cos-1 cells for transient expression of TPO gene. The cell culture media were analyzed with highly sensitive sandwich enzyme-linked immunosorbent assay (ELISA) 48 h after the transfection. Results The expression levels of the TPO gene elements followed the order of TPO intron v> TPOcDNA>ΔTPO intron I> TPO intron I> TPO gDNA in cos-1 cells. Conclusion The last intron of TPO gene obviously enhances the expression level of TPO gene, which can be inhibited by 5`UTR of TPO gene.