Abstract: In order to study the interactions of super absorbent polymer (SAP) and urea nitrogen in slow-release effect, using pot experiment, through analysis of the varieties of alkaline nitrogen in different growth period and all these provided the theoretical basis for an appropriate ratio of water-retention sustained-release fertilizer. The results showed that: in the early growth of corn, super absorbent polymer could hold available nitrogen, so that it would not be too fast to provide soil nitrogen for crop absorption; in the later growth period, soil available nitrogen content relatively smooth, description of these that super absorbent polymer could continue release of nitrogen into the available for uptake by maize; through variance analysis and test of significance, the main processing (SAP), secondary processing (urea) and main and auxiliary treatment interaction, in seedling stage and harvest stage alkali hydrolysable nitrogen reached very significant level, thus, super absorbent polymer had the capability of slow/controlled release of nutrient to meet the corn on nitrogen nutrient requirements, wherein, to handle the B3N2 interaction effect best, followed by processing B3N3.