Two experiments were conducted to study the effects of dietary type and in vitro storage conditions on the composition and character of jejunal juice in ducks. In experiment 1, a completely random design was used to study the effects of dietary type on the composition and character of jejunal juice in ducks. Thirty-six male adult ducks fitted with a T-cannula in the jejunum were randomly assigned to 2 groups with 6 replicates each and 3 ducks in each replicate, and fed corn-soybean meal diet and corn-soybean meal-rapeseed meal-cottonseed meal diet, respectively. The trial lasted for 35 days. In experiment 2, a 2×3 completely random design of two kinds of storage temperature (－20 and －70 ℃) and three storage periods (30, 60 and 90 d) was conducted to study the appropriate in vitro storage conditions of jejunal juice. Results showed that dietary type diets significantly affected the activities of trypsin, chymotrypsin and the concentrations of Mg2+ and Cl- of jejunal juices (P＜0.05). But the activities of amylase and lipase, the concentrations of K+, Na+ and Ca2+, pH were not significantly different in two treatments (P＞0.05). The storage temperature could significantly affect the pH (P＜0.05), but could not significantly affect (P＞0.05) the digestive enzyme activity of jejunal juice. The storage time could significantly affect the pH of jejunal juices in these two groups, and the activities of trypsin and amylase of jejunal juice in ducks fed corn-soybean meal-rapeseed meal-cottonseed meal diet (P＜0.05 or P＜0.01). In conclusion, dietary type was one of the important factors which could affect the biological characters of jejunal juice in ducks, and effects of storage conditions on the biological characters of jejunal juice could be dependent on the dietary type.［Chinese Journal of Animal Nutrition, ２００9，２1（5）:652-658］