Regulatory T cells (Tregs) specifically express forkhead box P3 (FOXP3) and CD25, which are indispensable components in the immune system to maintain immune self-tolerance and homeostasis. In recent years, Tregs that exist in non-lymphatic tissues have gradually obtained people's attention. Through genomics, proteomics, metabolic regulation and other in vivo and in vitro functional studies, it has been found that tissue-resident Tregs have unique phenotype that are different from circulating Tregs, and can perform some non-immune functions in addition to its immunosuppressive function in the tissues. By summarizing various functions of non-lymphoid tissue Tregs, we aimed to provide reference for studies on the functional mechanism of tissue-resident Tregs and treatment targeting tissue-resident Tregs.