In the research,five test groups were set,including urea at 0,120,240,360 and 480 kg/hm2,respectively,and analysis was conducted on mulberry leaf yield and some characters of the quality in order to establish utility functions of applied N in mulberry gardens with different production purposes and to provide schemes of rational N fertilization.The results indicated that yield of mulberry leaf and content and yield of active nutritional substances in the leaves would be reduced either by insufficient or excessive N quantity.In addition,240 kg/hm2 of applied N significantly improved active nutritional substances in leaf and 360 kg/hm2 of applied N significantly improved yields of mulberry leaf and active nutritional substances.Therefore,utility functions of applied N quantity with leaf yield,DNJ content and yield were established accordingly.The optimal N quantity in mulberry gardens for sericulture is recommended 360 kg/hm2 and the optimal N quantities in mulberry gardens for increase of yield and content of DNJ are 299.56 and 294.72 kg/hm2,respectively.