The effect of Lactobacillus casei fermentation on the protein molecular weight distribution， amino acid composition， total phenolic content， antioxidant activity， and tyrosinase and xanthine oxidase inhibitory activity was investigated in this study. Fermentation decreased the pH of defatted adlay， while increased the TTA. During fermentation， adlay proteins were hydrolyzed. Free amino acid content of adlay increased significantly during fermentation and 48 h fermentation brought about a 1.7 fold increase in total free amino acids compared to un-fermented adlay. Fermentation also substantially augmented the total phenolic content and the FRAP and ABTS values of both the water and ethanol extracts of adlay. Moreover， the fermented adlay showed higher inhibitory activity on tyrosinase and xanthine oxidase， with the increasing of 0.35 and 2.01 fold after 48 h fermentation， respectively. The results suggest that Lactobacillus casei fermentation could improve the nutrition quality of defatted adlay.