Severe pneumonia remains a critical global concern. The immune and cytokine imbalance mediated by lymphocytes are related to the severe transformation and tissue damage of pneumonia, and are expected to become potential therapeutic targets for severe pneumonia. This article elaborates on the protection and pathogenic mechanism of lymphocyte in severe pneumonia, and further introduces the clinical application and research status of host-directed immunotherapy in severe pneumonia from two aspects: enhancing host immunity and improving immunopathological damage. It also introduces the challenges faced by immunotherapy in the future clinical translational application, aiming to provide new thinking directions for its clinical diagnosis, treatment, and research.