OBJECTIVE: To systematically review evidence for the effect of convalescent plasma and immunoglobulin on treatment of severe acute respiratory syndrome (SARS), and further provide advice on the treatment of coronavirus disease 2019 (COVID-19). METHODS: Clinical studies of convalescent plasma and immunoglobulin in the treatment of SARS were collected from a variety of databases such as PubMed, Cochrane Library, Web of Science, Embase, CNKI, VIP, Wanfang, and CBM from November 2002 to March 2020. Two researchers independently screened the literature, extracted the data, and assessed the risk of bias based on the national institute for health and clinical excellence case series quality scale, and systematically evaluated the results. RESULTS: A total of 10 clinical studies, including 212 patients, were eventually included. There were 4 case series studies, 5 case reports and 1 case-control study. Most studies were with low or very low quality. The systematic analysis showed that 107 patients administered convalescent plasma and 16 patients used immunoglobulin during the treatment of SARS. Forty-nine patients were definitely not treated with the above two methods, and the remaining 40 patients were not reported clearly. The treatment of convalescent plasma and immunoglobulin could both improve the symptoms and reduce the mortality (12 died), and most SARS patients got better, while 11 SARS patients who did not receive the above therapies died. CONCLUSIONS: Convalescent plasma and immunoglobulin were effective on relieving symptoms of SARS patients. However, due to low quality and lacking of control group, convalescent plasma and immunoglobulin should be used with caution to treat COVID-19 patients.