Abstract: The present invention relates to the production of the receptor binding domain (RBD) of the Spike glycoprotein 1 of the SARS-CoV-2 in mammalian cell expression systems, and the successive method of purification thereof. A recombinant plasmid containing the coding sequence of said RBD is produced and transfected in said mammalian cells, for example, Expi293. A high level of the protein is secreted in the medium and subsequently purified using the N-terminal tag, that can be removed by a specific protease. The present invention also includes a recombinant expression vector carrying the RBD gene, the successive methods for protein purification, the strategy for establishing a stable cell line producing the RBD, methods of use of the recombinant protein in formulating a pharmaceutical composition, including but not limited to, vaccines for preventing SARS-CoV-2 induced diseases.