Interleukin-24 (IL-24) is a member of IL-10 family, which was cloned from human melanoma cells by the method of subtractive hybridization. IL-24 can inhibit the growth of tumor cells and angiogenesis and enhance radiation sensitivity and immune adjustment with non-toxic effects on normal cells.As a kind of cytokine with multiple anti-tumor functions, IL-24 will become a new weapon of gene therapy against cancer. The application and mechanism of IL-24 in the treatment of cancer will be discussed in this paper.