Coronaviruses are a class of RNA viruses that can cause respiratory and intestinal infections in animals and humans. SARS-CoV, MERS-CoV, and a novel coronavirus (SARS-CoV-2 [2019-nCoV]) belong to the family Coronaviridae and the genus Betacoronavirus. At present, the understanding of SARS-CoV-2 is getting deeper and deeper. In order to better prevent and treat SARS-CoV-2, this article compares the infectivity, pathogenicity, and related clinical characteristics of the three human pathogenic coronaviruses, SARS-CoV-2, SARS-CoV, and MERS-CoV to help us further understand the pathogenic characteristics of novel coronaviruses.