Abstract: Objective: To express and identify the human 4-1BB ligand fusion protein in E.coli.Methods: RT-PCR was used to clone CDS sequence of human 4-1BB ligand gene from Raji cells and construct pTrcHisB-h4-1BBL prokaryotic expression vector.After sequencing,the human 4-1BB ligand fusion protein was identified by Western blot assay.Results: Recombinant plasmid pTrcHisB-h4-1BBL was successfully constructed.The 6His-labeled human 4-1BB ligand fusion protein was expressed under induction of IPTG.Conclusions: Human 4-1BB ligand fusion protein was successfully expressed in pTrcHisB-h4-1BBL recombinant plasmid and it lays the foundation for further research on human 4-1BB ligand.