A 4 × 4 factorial experiment with four nonphytate phosphorus levels (0.17%, 0.25%, 0.33% and 0.41%) and four calcium levels (0.30%, 0.48%, 0.66% and 0.84%) was conducted to study the calcium and phosphorus requirements of Pekin ducks from 3 to 6 week of age. Six hundred and forty 15-day-old male Pekin ducklings were divided into 16 experimental treatments which contained 4 replicates and each replicate contained 10 ducklings, and these ducklings were raised with experimental diets from 15 to 42 days of age. The results showed that the daily weight gain and feed intake decreased significantly (P<0.05) as dietary calcium increased at 0.17% non-phytate phosphorus level,but the daily weight gain and feed intake exhibited up down quadratic trend at 0.25%, 0.33% and 0.41% non-phytate phosphorus levels; the tibia ash and tibia phosphorus decreased significantly (P<0.05) as dietary calcium increased at 0.17% nonphytate phosphorus level, but tibia ash increased significantly as dietary calcium increased (P<0.05) and tibia phosphorus was not influenced by dietary calcium level (P>0.05) at 0.33% and 0.41% nonphytate phosphorus levels. It is concluded that, according to the quadratic responding surface regression analysis, the requirements of calcium and non-phytate phosphorus for optimal daily weight gain and tibia phosphorus are 0.72% and 0.37%, 0.66% and 0.37%, respectively.