Abstract: To investigate the effect of N fertilizer on nutrient components of maize and rational N fertilizer treatment, the experiment, combining field experiment and laboratory analysis, was conducted to study protein, lipids, amino acids and vitamin contents of maize with different N fertilizer treatment. The results showed that, when the different input of N fertilizer was applied in different growth periods of maize (basic fertilizer was 68 kg/hm², at jointing stage was 52 kg/hm², at big trumpet stage was 30 kg/hm², at anthesis stage was 30 kg/hm², at grain filling stage was 45 kg/hm²), and the total input of N fertilizer was 225 kg/hm², protein and lipids contents were highest, which could reach 12.82% and 9.68%, and were 86% or 72% higher than that of the control (treatment 1), respectively. Also contents of all of detected amino acids and part of vitamins, including B1, B2 and B6, were higher than that with the others’treatment. With this treatment, the total input of N fertilizer was least. So rational treatment of fertilizer could not only improve the crop quality, but also decrease fertilizer input.