Antioxidant-rich plant foods can inhibit starch and lipid digestion that are relevant to the management of type-II diabetes. Our objective was to compare the three phenolic substances (total phenolic, total flavonoids, and condensed tannin content) in crude, semi-purified extracts from eight types of foods (purified by XAD-7 column), five fractions (semi-purified extracts fractionated by Sephadex LH-20 column) from black legumes, and to compare their antioxidant capacities. The IC50 values of these crude extracts, semi-purified extracts and fractions against alpha-amylase, alpha-glucosidase and lipase were measured. Results showed that Fraction V from black soybean had the lowest IC50 value (0.25 mg/mL) against alpha-amylase; Fraction V from black bean had the lowest IC50 value (0.25 micro gram/mL) against alpha-glucosidase; Fraction IV of black bean had the lowest IC50 value (76 micro gram/mL) against lipase; myricetin showed the lowest IC50 value against alpha-amylase, alpha-glucosidase and lipase.