To study the effect of different diets on digestive tract index and amylase activity of largemouth bass, digestive tract index and amylase activity of largemouth bass fed the formulated feed(feed group)and the ice fish (chilled group) were analyzed comparatively. The results indicated that the intestinal weight/body weight, hepatopancreas weight/body weight, splanchnic weight/body weight of feed group were significantly higher than those of the chilled group (P<0.05). The amylase activities in different organs were sequenced as follows:hepatopancreas > pyloric caeca > intestine > stomach in two groups. The amylase activities in hepatopancreas were significantly higher than those in other organs (P<0.05). For the amylase activities of chilled group and feed group, the optimum pH were 7.2 and 6.8,6.4 and 6.8,6.4 and 6.8,6.8 and 6.8 in stomach, hepatopancreas, pyloric caeca and intestine, respectively. The optimum temperature were 30℃ and 30℃,35℃ and 30℃,50℃ and 55℃,60℃ and 60℃, respectively. The concentration of starch were 8% and 8%,0.5% and 2%,8% and 8%,8% and 8%, respectively. The amylase activity of digestive organs in the feed group was significantly higher than that of the chilled group at same temperature and concentration of starch (P<0.05). The results would provide some reference for adding enzyme preparations and optimizing artificial feed formulation in the process of artificial feed preparation.