To improve maize (Zea mays L.) yield on the Loess Plateau many researches focused on high density, the water and fertilizer use efficiency, however, increasing productivity by high density is limited, because the influence of population characteristics is various. The corn production is a population process, optimized corn group structure can be helpful to augment production. The objectives of this study were to understand that the effects of maize cultivars intercropping on population growth characteristics in the field, and the dynamic changes of them during different growth stages. The experiment conducted on intercropping cultivation which interlaced with the same row spacing and mulch covered, used the two maize cultivars (zhengdan 958 and shendan 16) and two kinds of densities. Leaf area index (LAI), individual leaf area, plant height, stem diameter and dry matter accumulation were measured as growth characteristics. In contrast with monoculture, LAI of intercropping population showed significant increased when higher density. This may because a reasonable canopy compound structure is helpful for photosynthesis and dry matter production. Low-low density intercropping dramatically increased leaf area per plant. In the model of high-low density intercropping, leaf area per plant of the low density cultivar increased significantly, but high density varieties leaf grew less. High-high density intercropping reduced the individual leaf area significantly, compared with monoculture plants. Plant height and stem diameter of varieties increased slightly with the high intercropping density. The response of competition was correlated to the cultivars characteristics significantly, but the influence of intercropping density was insignificant. Intercropping has significant increase in dry matter accumulation, especially in zhengdan 958. With the increase of density intercropping, the plant height and stem diameter reduced and the quantity of accumulation decreased. The morphological characteristics of zhengdan 958 at the vegetation stage and reproduction stage performed an obvious, sustainable, and stable response to intercropping-competition, but shendan 16 did not. The differences of growth between the intercropping and monoculture minimized gradually at the reproduction stage. Dry matter accumulation of shendan 16 was faster at the vegetation stage but only for a short time, indicated an unstable competitive performance. It is concluded that cultivars-intercropping improves the population's canopy structure and increases the productivity of dry matter effectively, lays the great foundation for the maize yield.