The invention provides polypeptide food therapy flour of diabetics and a preparation method thereof, which belong to the field of food. The polypeptide food therapy flour comprises the following raw materials in parts by weight: 10-40 parts of wheat flour, 5-35 parts of momordica charantia polypeptide extracts, 10-20 parts of inulin, 5-10 parts of cucumber powder or tomato powder, 1-5 parts of konjaku flour, 1-10 parts of white kidney bean powder, 5-15 parts of kelp powder, 0-5 parts of nutritional yeast powder and 0.01-0.05 part of a complex enzyme preparation. The polypeptide food therapy flour provided by the invention is rich in hpyerglycemic momordica charantia polypeptide proteins and plant polysaccharide that are extracted and purified effectively and is high in the content of dietary fibers; through animal experiments and feeding trials, the postprandial blood sugar of the diabetics is effectively reduced, the function of a damaged pancreas islet can be improved, and the living quality of the diabetics is improved. The invention also provides the preparation method of the polypeptide food therapy flour of the diabetics.