Objective：To construct the recombinant plasmid containing SRY related high mobility group box 18（SOX18）gene and investigate the effect of the recombinant protein on angiogenesis of vascular endothelial cells. Methods：The whole sequence of SOX18 gene that amplified from human umbilical vein endothelial cells（HUVEC）by reverse transcription-polymerase chain reaction（RT-PCR）were inserted into the expression plasmid pSecTag-2B to construct the recombinant vector，and termed as pST-SOX18. pST-SOX18 was then transfected into the HEK293T and vascular endothelial cells，respectively. Subsequently，Western blotting was carried out to determine the expression of the recombinant protein. CCK-8 assay was used to assess the effect of pST-SOX18 on proliferation of vascular endothelial cells. Results：The recombinant plasmid pST-SOX18 was constructed successfully. pST-SOX18 was successfully transfected into HEK293T and vascular endothelial cells，target protein was determined by immunoblotting. pST-SOX18 transfection significantly promoted vascular endothelial cell proliferation in vitro. Conclusion：The recombinant plasmid expressing functional SOX18 was constructed successfully. SOX18 have a potent potential in promoting the proliferation of vascular endothelial cells.