Abstract: Regulatory T cell (Treg) is a subset of T cells that negatively regulates immunity and has the function of inhibiting rejection. The specific modification of Treg by chimeric antigen receptor (CAR) technology can successfully chime donor-specific antigen onto the surface of Treg, thus regulating the immune function of the body in a real-time manner. It provides a novel and promising therapeutic option for inducing immune tolerance. In this article, research progresses on Treg in immune related diseases, main difficulties in the realization of CAR-Treg technology and its role in inducing transplantation immune tolerance were reviewed, and the opportunities and challenges of CAR-Treg application in the field of organ transplantation are prospected.