Abstract: Evidence suggests that nitrogen, the highest input nutrition in agriculture, affects the yield advantage of many intercropping systems. However, it is unclear that how crop respond to nitrogen input in the maize and potato intercropping system which is an overyielding and widespread system in the world. A field experiment was conducted to explore productivity, shoot biomass, interaction and growth of the intercropped maize and potato under the nitrogen input condition. The results show that the nitrogen input could reduce the LER in the maize and potato intercropping, and the competition ability of maize is significantly strengthened at the early flowering stage for maize under the nitrogen input condition. At the harvest time, The leaf biomass, leaf area and ratio of stem and leaf are significantly increased for intercropped maize under the nitrogen input condition, while those of potato are decreased. There is no statistically significant difference on the specific leaf area for both crops. These findings suggest that the interspecies competition between maize and potato increase under the nitrogen input condition reduces the yield advantage.