Interleukin-33 (IL-33) is a new member of the newly discovered IL-1 family, which induces the production of Th2 type cytokines by binding to its receptor ST2. IL-33 can regulate Th2-type immune response, stimulate premature inflammatory factors in mast cells, and regulate gene transcription as a nuclear factor. IL-33 plays an important role in vascular diseases, allergic diseases, autoimmune diseases, and inflammatory diseases. Research on the function and mechanism of IL-33 will help to further understand the pathogenesis of these diseases and provide new strategies for disease treatment.