The invention discloses a tartary buckwheat D-chiral-inositol composite hypoglycemic tablet and a preparation method thereof. The tartary buckwheat D-chiral-inositol composite hypoglycemic tablet is prepared from the following original auxiliary materials in percentage: 15-30% of tartary buckwheat D-chiral-inositol concentrated solution, 3-5% of bitter gourd concentrated solution, 3-5% of mulberryconcentrated solution, 3-7% of cassia obtusifolia concentrated solution, 3-7% of american ginseng concentrated solution, 3-7% of orange peel concentrated solution, 3-5% of honeysuckle concentrated solution, 4-8% of the root of kudzu vine concentrated solution, 4-8% of astragalus membranaceus concentrated solution, 7-14% of purslane fungistat, 6-10% of pumpkin polysaccharide, 6-13% of black funguspolysaccharide, 7-16% of soybean hypoglycemic peptide, 3-20% of xylitol, 3-10% of maltitol, 0.3-0.8% of citric acid, 3.4-8.7% of beta-cyclodextrine, and 0.5-1% of magnesium stearate. The tartary buckwheat D-chiral-inositol composite hypoglycemic tablet has the characteristic that tartary buckwheat extracts with high content of D-chiral-inositol are used as raw materials to prepare a composite tablet with the hypoglycemic effect. The tartary buckwheat D-chiral-inositol composite hypoglycemic table takes natural plant hypoglycemic active ingredients as the original auxiliary materials and a purslane active ingredient as a natural antibacterial agent, and is safe, reliable and edible.