Abstract: To ascertain the population characteristics of high-yield maize in Ningxia and the factors that limit high yield, ‘Zhengdan 985’ and ‘Xianyu 335’ were chosen as the experimental cultivars with the planting densities of 121215/hm² and 110205/hm². Yield and yield components, the group photosynthetic characteristics at key growing stages and the dynamic change of dry matter were studied. The results showed that: leaf area index (LAI) showed unimodal curve change and reached the highest value around silking stage. The photosynthetic effective radiation showed a sharp decreasing trend with the canopy downward and the change of light transmittance was the most obvious at the position of 120-180 cm. The dynamic change of dry matter accumulation showed an ‘S’ shaped curve in the whole growth period and it reached the highest at the maturity stage. High yield could be obtained by following the two different modes of yield potential digging. ‘Xianyu 335’ was more ideal for achieving high yield but the lack of nitrogen supply at the late growing stage was the limiting factor for high yield achievement. Therefore, in the original density of ‘Xianyu 335’, increasing N fertilizer application at the late growing stage to increase 1000-kernal weight and grain number per ear was an important way of further increasing maize yield in Ningxia.