Human angiotensin converting enzyme 2 (hACE2) mediates the cell entry of both SARS-CoV and SARS-CoV2 and can be used as a drug target . The DNA encoding the truncated hACE2 (30-356aa) was cloned into pET-28a (+) and expressed in Escherichia coli Rosetta (DE3). The recombinant hACE2 (rhACE2) was purified by affinity chromatography on a Ni-NTA column and characterized with SDS-PAGE and Western blot . The binding activity of rhACE2 to Spike protein of SARS-CoV2 was evaluated in S protein-overexpressed HEK293A cells (HEK293A-SP cells) through flow cytometry . The prokaryotic expression system is able to produce approximately 75 mg protein per liter, which would be useful for infection mechanism study, and drug screening and development of SARS-CoV2.