Objective To construct the eukaryotic expression vector of CD20 and overexpress soluble CD20 proteins in HEK293T cells. Methods The total RNA from human peripheral blood mononuclear cells (PBMCs) was used to amplify the coding sequence of CD20 by reverse transcription PCR, and then the CD20 gene was cloned into the expression vector pCMV3-C-His. After PCR and sequencing validation, the recombinant CD20 protein was transiently expressed in HEK293T cells and detected by ELISA and Western blot analysis. Moreover, the expression conditions were optimized to improve the expression level of CD20. Results The coding sequence of CD20 was successfully cloned into eukaryotic expression vector pCMV3-C-His. After 72 hours of transfection, the expression of CD20 was detected both in intracellular and supernatant by Western blot analysis. The passage number of HEK293T cells was related to the expression level of CD20 in supernatant. Conclusion The coding sequence of CD20 was successfully cloned into the eukaryotic expression vector, and CD20 was over expressed in HEK293T cells.