Abstract: T helper17 cells ( Th17 cell ) have been recently identified as part of the CD4+ T helper cell lineage. It has a unique mechanism of differentiation and development. With the participation of several cytokines, such as transforming growth factor beta ( TGF-β ), interleukin 6, and interleukin 23, and the orphan nuclear receptor ( RORγt ) of specific transcription factors, the initial CD4+ cells differentiate and develop into Th17 cells. The activated Th17 cells can trigger inflammations and diseases by secreting the cytokines, including interleukin 17, interleukin 21, and interleukin 22. Th17 cells play an important role in infectious diseases, autoimmune diseases and graft rejection reactions. However, the role of these cells in tumor immunity is unknown. Th17 cells and their cytokines have recently been found in several human malignancies and peripheral blood smears. Concerning the role of Th17 cells in the onset and progression of tumors, whether they facilitate or inhibit tumor growth remains controversial. Over the past few years, it has become the focus in research on tumor immunity. The studies on Th17 cell expression in tumors and its underlying mechanism can provide a theoretical basis for specific Th17-targeted tumor therapy.