Coronavirus Disease 2019(COVID-19) caused by 2019-nCoV was in an outbreak globally. A large number of severe cases lead to strong clinical pressure even treated actively. Convalescent plasma (CP) therapy refers to a therapy infusing plasma from recovered donors into other infected individuals. It has played an important role in conquering variety of epidemics over a century with some limitations. Considering the absence of specific treatments, CP has been used for treating COVID-19 and achieved some efficacies. This article provides a reference for clinical application of CP therapy in COVID-19, by discussing the history, mechanism and application of CP therapy in viral diseases such as SARS.