Immunosenescence is the most significant change in immune system with aging. It is closely associated with infectious diseases, autoimmune diseases and malignant tumors, and leads to the progression of severe coronavirus disease 2019 (COVID-19) in the elderly after SARS-CoV-2 infection. Immunosenescence changes the frequency, phenotype and function of immune cells in the innate and adaptive immune systems, results in immune dysfunction and imbalance of inflammatory response, and thus increases the risk of death and adverse prognostic events in elderly patients. In this article, we analyzed the relationship between immunosenescence and severe COVID-19 in order to explore effective treatment of severe COVID-19 in the elderly and improve the survival and prognosis of the elderly patients.