Abstract： The novel coronavirus 2019 (COVID-19) infected patients by binding human ACE2,leading to severe pneumonia and highly mortality rate in patients.At present,there is no definite and effective treatment for COVID-19.ACE2 plays an important role in the RAS,and the imbalance between ACE/Ang II/AT1R pathway and ACE2/Ang (1-7)/Mas receptor pathway in the RAS system will lead to multi-system inflammation.Increased ACE and Ang Ⅱ are poor prognostic factors for severe pneumonia.Animal studies have shown that RAS inhibitors could effectively relieve symptoms of acute severe pneumonia and respiratory failure.The binding of COVID-19 and ACE2 resulted in the exhaustion of ACE2,and then ACE2/Ang (1-7)/Mas receptor pathway was inhibited.The balance of the RAS system was broken,and this would lead to the exacerbation of acute severe pneumonia.Therefore,we speculate that ACEI and AT1R inhibitors could be used in patients with COVID-19 pneumonia under the condition of controlling blood pressure,and might reduce the pulmonary inflammatory response and mortality.