Abstract: Maize crop nitrogen demand is high, with the crop yields to improved in recent years, series of environmental pollution and low use efficiency of crops caused by excessive nitrogen.The crop root growth can lay a solid foundation for growth and improving post-production. In this study,Zheng 58 maize and Chang 7-2inbred lines,and their hybrids Zheng 958 as materials, using liquid culture method to study the 0.02 mM,0.20 mM,2.00 mM,10.00 mM,20.00 mM （where 2.00 mM concentrations as control） nitrate concentrations seedling biomass,root morphology and determination of nitrate under three maize varieties content,the results showd that the concentration of nitrate at low stress, elongation of maize seedling lateral inhibition, root and shoot dry weight was inhibited,the inhibition of the more notable shoot, shoot ratio increased performance;high concentrations of nitrate under stress seedling lateral length and density, root and shoot dry weight decreased,but the nitrate content in the body continued to rise, indicating that luxury was not directly related to absorb the growth of maize seedlings.Offspring root length, vivo nitrate content and dry matter accumulation was significantly higher than that of the parent, it indicated that the huge roots help absorb more nutrients,produced more dry matter to show heterosis offspring.