The total nitrogen in the same circumstances，Nitrogen was applied on Spring wheat in different times and differ- ent rates.Study showed: Two varieties showed a consistent trends under nitrogen application. After 14 days of flag leaf out- spread，leaf area index，photosynthetic rate，soluble protein contents，superoxide dismutase showed N2>N3>N1 . Malon- dialdehyde showed N1>N3>N2 . Two varieties gain high yield in treatment of N2 ，N3 . This experiment suggested that nitro- gen used respectively and late were conducive to accumulate plant substances， reduce the level of lipid peroxidation in the late，maintain a high level of protection activity，prolong the function of leaves， improve yield.