This study was conducted to determine the effects of maize naturally contaminated with aflatoxin B1 (AFB1) on growth performance, intestinal morphology, relative digestive organs weight, digestive enzymes activities, and biochemical index of intestinal development in ducks. A total of 640 ducks was blocked on the basis of sex and body weight, and then allocated randomly to 2 treatments with 20 pens per treatment and 16 ducks per pen. The experiment lasted for 5 wk, and dietary treatments included basal diet (CON) and diets with 100% of normal maize replaced by AFB1 contaminated maize. Detectable levels of other toxins were present but only AFB1 exceeded limits and the level of AFB1 was 195.4 ug/kg in the contaminated maize, and ranged from 2.91 to 120.02 ug/kg in the starter diet and 2.03 to 153.12 ug/kg in the grower diet. Feeding AFB1 contaminated diets decreased (P < 0.05) ADG and ADFI during the whole experiment, whereas F/G during d 15 to 35 and d zero to 35 was reduced (P < 0.05). The mortality of ducks fed AFB1 contaminated diets increased (P < 0.05). Ducks fed AFB1 contaminated diets had greater (P < 0.05) relative weights of proventriculus and gizzard on d 14 as well as the duodenum, jejunum, and ileum on d 14 and 35. Feeding AFB1 contaminated diets increased (P < 0.05) crypt depth, villus width, and surface area in the duodenum on d 35 and villus height, villus width, and surface area in the jejunum on d 14. The activities of alkaline phosphatase and leucine aminopeptidase in the jejunum brush border together with chymotrypsin and trypsin in the pancreas increased (P < 0.05) on d 14 with the inclusion of AFB1 contaminated maize. The jejunum villus became long and wide in ducks fed AFB1 contaminated diets. Taken together, the feeding of maize naturally contaminated with AFB1 caused adverse effects on growth performance and intestinal morphology, and altered digestive physiology and development.