Abstract:T helper cells are the major effector lymphocytes in adaptive immune responses. Th1 and Th2 cells were the initial understanding T helper cells in mouse and human. In recent two decades, new lineages of T helper cells were described, including Th9, Th17, Th22, Tfh and Treg cells. Currently, the phenotypic characteristics, immunological functions and differentiation mechanism of new subset of Th cells are main immunological research topics. The concept of Th cell plasticity makes research more complicated, especially, Th cell polyfunction, the cell to cell interaction and differentiation mechanism are needed to be further understood. We mainly focus on the latest highlights about Th9, Th17, Tfh and Th22 cells, and summarize the functions of new T helper cells, differentiation plasticity and its mechanism.