Abstract: Quantitate diagram models are developed which illustrate the macroscopic features with its temporal changes of N transformation and circulation in Chinese agroecosystem,by using a simplified model of N cycling with 3 untrient pools of crop, livestock and soil.The results indicated an increasingly intensified tendency that Chinese agriculture is becoming more inorganic and less efficient.While the total crop biomass N product,the food N supply and the proportion of animal N in total food N were increased 2.3, 2 and 4 times more respectively in Chinese crop-livestock system by the end of nineteen eighties than at the beginning of ninetenn fifties,the total production N input and N fertilizerconsumption were increased in 8 and 187 times,with simultaneous lowering in the proportion of organic to total production N input from 97% to 25%,and decreasing the production efficiency of total and inorganic N input in terms of producing main product N from 1.12 and 3.63 to 0.34 and 0.46 respectively.The supply of forage N would have to be doubled to tripled and fertilizer N consumption more than doubled in order to meet the food N demand of an improved quality for the population grown to 1.3-1.5 billions,this would brings out serious environmental consequences.Possible options of ecological agriculture strategy are also discussed in its potentials of dealing with challenges in respect to the N transformation and circulation in Chinese agroecosystem.