Abstract: Effects of three controlled-release nitrogen fertilizers on summer corn carbon and nitrogen metabolism were studied under field condition. The results showed that，at the same nutrition rate, in comparison of traditional fertilizer, all the three controlled-release nitrogen fertilizers could effectively harmonize the index of carbon and nitrogen metabolism from silking to maturity stage. The soluble protein content and reductase nitrate（NR）activity in leave was increased by 2.20%-10.39%, 3.22%-32.10%, respectively; And the soluble sugar content, nitrogen content in leaves and stem and sheath were increased by 6.78%-46.71%, 0.50%-10.69% and 1.26%-35.99%, 1.09%-41.92%, respectively. The increase of these index indicated that controlled-release nitrogen fertilizer could synchronize the nutritional requirements of summer maize growth, consequently harmonize the carbon and nitrogen metabolism.