Abstract: In order to determine the effects of controlled and slow release fertilizers on the N utilization and grain yield in summer maize under different plant densities, medium and high rates of controlled and slow release fertilizer (i.e. 750 kg/hm2, 975 kg/hm2) were applied under medium and high plant densities (6.75×104, 8.25×104 plant/hm2), summer maize cultivar ‘Zhengdan 958’ was used for this study. The treatment of 750 kg/hm2 controlled and slow release fertilizer level under medium plant density (6.75×104 plant/hm2) was as control. The effect of controlled and slow release fertilizer on the N concentration in either individual plant organ or total plant was insignificant. However, the increase supply of controlled and slow release obviously deceased the plant bare rate by 20.0% compared with the medium supply of controlled and slow release fertilizer, especially under high plant density (decrease by 27.0%), and the average ear weight increased by 12.4%. Although the effect of controlled and slow release fertilizer on grain yield was insignificant, the average yield of high supply of controlled and slow release fertilizer under high plant density was increased by 15.0%, 19.4% compared with control, and medium supply of controlled and slow release fertilizer under the same plant density, and the economic efficiency was also increased by 12.3% compared with control. It is thus concluded that high supply of controlled and slow release fertilizer (975 kg/hm2) under the high plant density (8.25×104 plant/hm2) could further increase the grain yield and economic efficiency.