Abstract: Field experiment, plant physi-biochemical analysis and scanning electro-microscope observation were used to investigate the effects of nitrogen application on sugar and starch formation in high starch maize of Jidan 535, compared with the ordinary maize of Jundan 8. The results indicated that for two maize cultivars, starch concentration in grain increased when N application rate was from 0 to N 200 kg /ha, while decreased when N was over N 200 kg /ha. The concentration of sucrose, fructose and glucose in Jidan 535 was higher than Jundan 8 at grain filling, and higher concentration of sucrose, fructose and glucose in the grain of two maize cultivars was acquired under appropriate N application. Starch granule in the grain of Jidan 535 was full of cell uniformly, and starch granules in the grain of Jundan 8 were arranged in a confusion form. Appropriate N application led starch granule arranged uniformly, but starch granule was squeezed to the status of polyhedron with excessive N application.