In order to know the waste nitrogen flow and its environmental effects in the food chain, the crop production- livestock breeding-household consumption system in Suzhou City was studied. Results showed that 5.35×10⁴ t waste nitrogen were produced, 59.76% of which were from human food consumption and 57.53% of which were lost into environment. The nitrogen recycling rates of crop straw, animal excrement, food residue and human excrement were 84.03%, 49.26%, 37.72% and 21.99%, respectively. 1.70×10⁴ t waste nitrogen were transported into water, and the concentration was 4.30 mg/L, which is 4.3 folds of the three-level standard of water environmental quality. The atmospheric environmental waste nitrogen load was 5.8×10³ t and most of the pollutants stemmed from human and animal excrement, mainly in the form of ammonia. The farmland load warning value ranged from 0.15 to 0.22, belonged to the first level and signified non-pollution. Path analysis showed that population, policy and science-technology are the strongest driving forces for the waste nitrogen discharged in environment. Therefore, comprehensive measures in agricultural production and waste management could be taken into practice to improve the environment in Suzhou City, such as fertilizing more excrement, reusing straw diversely, managing excrement scientifically, and processing food residue specially.