The trial was conducted to study the effect of phytase on energy, nutrient availability and digestive enzyme activities of cherry valley meat ducks. Six hundred one-day-old healthy ducks were randomly divided into 5 groups with 6 replicates and 20 ducks in each replicate. The dietary treatments were as follows: group I was basic diet without phytase as the positive control group; group II was basic diet with reduced AP as the negative control group; group III was diet II with plused 500 U/kg phytase; group IV was diet II with plused 1 000 U/kg phytase; group V was diet II with plused 10 000 U/kg phytase. The results showed that: 1) compared with group II, energy apparent utilization and crude lipid true utilization of 21-day-old meat-strain ducks were increased significantly by 3.18% and 13.27% in group IV (P<0.05), respectively; apparent utilization of dry matter and crude protein, apparent and true utilization of crude lipid of 42-day-old meat-strain ducks were increased significantly by 10.07%, 9.45% and 17.49% in group IV (P<0.05), respectively; 2) compared with group II, apparent availabilities of Ser, Gly, Cys and Phe were increased significantly at the age of 21 days (P<0.05), as well as that of Gly, Ala, Met, Ile and Tyr at the age of 42 days (P<0.05); 3) at the age of 21 days, protease and disaccharidase activities in jejunum in group IV were increased significantly by 14.29% and 17.87 than that in group II (P<0.05); at the age of 42 days, trypsin activity in group IV and lipase activity in group III and IV in jejunum were significantly improved compared with that in group II (P<0.05). Results indicated that phytase supplementation in the pellet diets of ducks could improve nutrient availability and digestive enzyme activities, and the optimal supplemental level of phytase was 1 000 U/kg.［Chinese Journal of Animal Nutrition, 2009，21(6):938-944］