Since the discovery and spread of coronavirus disease 2019 (COVID-19), it has aroused widespread concern from all walks of life. There are different opinions on the relationship among angiotension converting enzyme (ACE)/ACE2, renin-angiotension system (RAS) inhibitors and COVID-19 in medical circles. ACE and ACE2 are similar in structure but have opposite effects. The positive ACE-AngⅡ-AT1R axis and the negative ACE2-Ang(1-7)-Mas axis in vivo check and balance each other to maintain the stability of blood pressure and internal environment. A number of basic studies have shown that different RAS inhibitors have inconsistent effects on ACE2. The causal relationship between ACE2 and COVID-19 has not been clarified, and no clinical evidence has been found that the use of RAS inhibitors aggravates COVID-19. The consideration of ACE2 influencing COVID-19 is basically derived from the theoretical derivation of RAS and the inference of the basic research results of SARS. Whether cardiovascular disease patients with COVID-19 use RAS inhibitors should be combined with clinical practice and weighing the pros and cons. Evidence-based RAS inhibitors cannot be arbitrarily discontinued in the current ambiguous situation.