Abstract: Regulatory T cells(Treg) play an important role in inhibiting the activity of immune cells targeting self-antigens and controlling inflammation caused by autoimmune diseases. Expanding Treg cells and taking advantage of their immunosuppressive function are promising means for the treatment of autoimmune diseases and organ transplantation. Currently, Treg cell therapy in graft-versus-host disease (GVHD) and autoimmune diseases has received wide attention, and its therapeutic potential is being verified in a number of clinical trials related to autoimmune diseases. The application advances of Treg cell therapy in autoimmune diseases and organ transplantation are reviewed in order to provide some reference for the research on Treg cell therapy.