[Objective]To study the effect of supplies of nitrogen level on spring maize leaf blade carbon metabolism.[Method]In this experiment,field trail and biochemistry analysis were used to study the effect of the diference-nitrogen level on the content of chlorophyl and carboxylase activity of RuBP and PEP in the leaf of spring maize during main growing period.[Result]Applying proper amount of N could keep relative higher content of chlorophyl and higher activity of carboxylase of RuBP and PEP in the leaf of spring maize,insufficient or excessive（N 400 kg/hm^2） of nitrogenous fertilizer has the adverse effect.[Conclusion]In this experiment,applying 300 kg/hm^2 amount of N could keep relative higher content of chlorophyl and higher activity of carboxylase of RuBP and PEP in the leaf of spring maize during main growing period.It was important to strengthens the leaf blade photosynthesis ability,promote the yield formation and postpone the decline of leaf blade.
