The high incidence of coronavirus disease 2019 (COVID-19) and high mortality of critical patients have posed a great challenge to global public health resources. Currently there are no specific antiviral drugs and vaccines available for COVID-19, which has drawn the attention to the usefulness of convalescent plasma (CP) again, so the application of CP in the adult patients with COVID-19 is reviewed. The main contents include the possible mechanism of CP, the evidence of CP in the treatment of COVID-19 patients, the safety of clinical application of CP and the main factors affecting the clinical effect of CP, which may provide some basis for clinicians to choose CP for the treatment of adult patients with COVID-19.