Abstract: Effects of mixed cropping of maize and peanut on the N nutrition in cropping system were studied.The results indicate that mixed cropping density of maize and peanut(peanut∶maize=5∶3)has no significant effects on biomass,total N and N uptake per plant of maize and peanut,but can obviously reduce NO^-₃-N concentration in the rhizosphere of peanut and improve peanut nodule number and peanut nodule nitrogenase activities(ARA)per plant peanut.