Granzyme A (GzmA) is a serine protease secreted by natural killer cells and cytotoxic T lymphocytes. It can regulate the body's immune defense by inducing apoptosis and pyrolysis, and it can also kill bacteria and parasites that invade the host cells to maintain body homeostasis. Recent studies have found that GzmA influences the pathogenesis and development of tuberculosis, sepsis, and rheumatoid arthritis by regulating the release of IL- 6 and TNF-伪, and also it can activate pSTAT 3 to promote the development of intestinal inflammation and colorectal cancer. This article reviews the characteristics and functions of GzmA, as well as its role in inflammatory process, autoimmune diseases and tumors.