To study the effects of duodenal infusion of soybean small peptides on milk composition, blood biochemical indices and mRNA expression of PepT1 in small intestine, twelve Chinese saanen lactating goats with an average body weight of (38±2) kg with duodenal fistula were divided into four groups and were infused 0, 60, 120 and 180 g/d soybean small peptides, respectively. The infusion period lasted for 14 d. The results showed: 1) yield (P<0.05) and percentage of milk protein were increased and the effect was significant in 120 g/d treatment （P<0.05）. Milk fat yield and content were decreased with increasing infusion of soybean (P<0.05). Milk urea nitrogen was increased with the increase amounts of soybean small peptides infusion (P<0.05); 2) in serum, the contents of total protein and globulin were numerically higher in soybean small peptides treatments than those in control group and the effect was significant in 120 g/d treatment （P<0.05）. The albumin content in serum was lower compared with the control group (P<0.05). The contents of urea nitrogen and growth hormone were increased with the increment of amounts of soybean small peptides infused (P<0.05), and that of insulin was numerically increased (P>0.05), but the effect was significant only in 180 g/d treatment （P<0.05）; 3) mRNA expression of PepT1 in duodenum, jejunum and ileum was increased with increasing amount of soybean small peptides infused. In soybean small peptides treatments, mRNA expression of PepT1 in duodenum was 1.6, 2.6, 5.4 folds, that in jejunum was 1.1, 1.4, 3.3 folds and in ileum was 1.1, 1.8, 2.4 folds higher than that in control group, respectively. With the increasing amount of soybean small peptides infused, PepT1 expression in duodenum was 1.5 and 1.6 folds higher than that of jejunum and ileum in 180 g/d treatment. The current results suggested that the mRNA of PepT1 in small intestine was increased by small peptides infusion, and the absorption of small peptides and milk protein synthesis were improved. The effect was best in 120 g/d treatment.