Type 1 diabetes mellitus (T1DM) is an autoimmune disease in which pancreatic β cells are destroyed, resulting in an absolute lack of insulin. Intestinal microbiota and its metabolites can promote the progression of T1DM by destroying pancreatic β cells, increasing insulin resistance, increasing intestinal permeability, interfering with immune response. Therefore, fecal microbiota transplantation is expected to become a new method for preventing and treating T1DM in the future. This article mainly explores possible pathways for the application of fecal microbiota transplantation in T1DM, including protection of pancreatic β cells, improving insulin resistance, reducing intestinal permeability, and regulating immune responses.