Abstract: Th17 cells have important functions in several diseases, including autoimmunity, inflammations, allergies, and tumors.However, the function of these cells in most tumor immunity cases remains unknown.The current study reviewed the current understanding of molecular interactions, signal pathways, and cell migration that contribute to cell differentiation and functions of Th17 cells in a tumor microenvironment.This paper also summarized the conclusions regarding the functions of these cells in tumorigenesis to provide basic guidelines for Th17-targeted therapy of tumors.