This study was conducted to investigate the protein requirement for growing Dorper sheep. A 2×3 factorial design were used, and the factors were sex (ram and ewe) and dietary crude protein (CP) levels. The effects on performance and nitrogen balance of Dorper sheep were investigated in feeding and metabolism tests. The results showed that there was significant difference in average daily gain (ADG) of Dorper sheep under the three dietary CP levels (P<0.05), and the ADG in high CP group (222.31 g/d) was the highest, followed with that in middle CP group (186.57 g), and the lowest was that in low CP group (121.43 g); the requirement of 1 g weight gain for rams was 0.44 g, and that for ewes was 0.42 g. The formulas of requirement of CP and digestible CP of growing Dorper sheep were as follows: ram, RCP=3.87W^0.75+0.44△W (R²=0.981), RDCP=2.48W^0.75+0.28△W (R²=0.979); ewe: RCP=3.86W^0.75+0.42△W (R²=0.977), RDCP=2.46W^0.75+0.28△W (R²=0.962).