This study was carried out to investigate the photosynthetic elements with different light intensity un-der five planting density of maize using Zhengdan 958 and Xianyu 335 as material. The results showed that the netphotosynthetic rate were increased with light intensity when light intensity in the range of 1300~1900 μmol·m^-2·s^-1. It had the highest net photosynthetic rate when the light intensity reached 1700μmol·m^-2·s^-1and 1900μmol·m^-2·s^-1for every planting density. Under the same light intensity, it had the maximum net photosynthetic rate at 30 000plants/ha planting density, and the minimum net photosynthetic rate at 90 000 plants/ha. Although suitable compactplanting reduced single plant photosynthetic capacity, but the light energy utilization rate of group was significantlyimproved and it was beneficial to group dry matter accumulation and increase of yield.