Regulatory T cell（Treg） is a thymus-derived T lymphocyte lineage with the ability of immunosuppression in the periphery， and it plays a key role in autoimmune diseases， immune tolerance， immune system， tumor immunity， transplantation immunity， allergic reaction and many other pathological immune processes. Natural Treg cell （nTreg） or called thymus regulatory T cell （tTreg） is a very important T cell lineage in Treg cells. In this paper，we make a review of this T cell lineage on the process of their differentiation，development and proliferation and the regulatory mechanism of them.