Anaerobic acidogenesis provides a novel pathways to reutilize soy sauce residue.The results showed that the efficiency of anaerobic acidogenesis was improved along with decreasing F /M.When F /M was 1 ∶ 1,more VFA,especially acetate,was produced from soy sauce residue.The degradation rates of soluble proteins and carbohydrates were highest with 71.23% and 73.43%.The activities of acid-protease,neutral-protease,alkaline-protease and α-amalyse were also highest with 4.116 U /mL,3.812 U /mL,3.049 U /mL and 13.72 ug maltose /min,respectively.The yields of the total organic acids and acetatic acid per unit substrate were 0.17 g /mL and 0.14 g /mL.And,the percentage of acetatic acid in the total VFA amounted to 82.19%.The conversion of soluble proteins at the beginning period of fermentation was due to the catalytic degradation of acid-protease.The fermentation products involved in ethanol,acetatic aicd,propionatic acid,iso-butyratic acid,butyratic acid and valeratic acid.A certain amount of propionatic acid accumulated during the anaerobic acidogenesis.Under 20∶ 1 F /M,the concentration of propionatic acid was highest with around 4.00 g /L.