The reasonable plant density was the base of constructing the good population and optimum population physiological functions of maize, the suitable nitrogen application was the base of nutrition matter of maize photosynthate production. The D-saturation optimum design and crop population physiology were used to investigate the effects and relationships of plant density and nitrogen fertilization on population physiological indexes and yields of summer maize in Guan-zhong irrigated zone. The results showed that the relationship of plant density and grain yield，DMA(dry matter accumulate), MLAI(max leaf area index), LAD(leaf area duration), CGR(crop growth rate)are positive in the range of 45000-75000 plants/hm2; The relationship of grain yield and leaf NAR(net assimilation rate)were negative in the range of 45000-60000 plants/hm2, while its were positive in the range of 60000-75000 plants/hm2. The relationship of nitrogen application and grain yield, DMA, CGR were positive when nitrogen were less applied 600.0kg/hm2 per hectare. When nitrogen were less applied 260.55 kg/hm2 per hectare, the relationship of nitrogen application and MLAI, LAD were positive while the relationship of nitrogen application and NAR were negative. During the nitrogen application range of 260.55-600.0kg/hm2, the relationship of nitrogen application and MLAI, LAD were positive while the relationship of nitrogen application and NAR were negative. The influence of plant density on grain yield, DMA, MLAI, LAD, CGR were higher than that of NAR. The influence of nitrogen application on grain yield，DMA, NAR, CGR were higher than that of MLAI, LAD. The effect on the grain yield and population physiological indexes of maize Shandan8806 were more significant than that of nitrogen application, summer maize shaandan8806 should be reasonable plant density in its production. The optimum technology programs of the factors of summer maize in Guan-zhong irrigated zone were given: the optimum combinations of plant density date and nitrogen application were 61713-66177 plants/hm2 and 309.88-569.02 kg/hm2 respectively under the conditions of the experiment.