Abstract: Based on in situ measurements of ammonia volatilization and nitrous oxide (N2O) emission from a wheat-rice rotation field, as a representative of cropping system in Yangtze Plain, the reliability and sensitivity of Denitrification-Decomposition model (DNDC) for forecasting nitrogen cycling and balance were tested in field scale, and influencing factors of various N cycling pathways were identified. A higher reliability was found between soil ammonia volatilization and N2O emission simulated by DNDC model and field results, suggesting that the DNDC model could be used for describing nitrogen loss under different nitrogen fertilizer managements. According to sensitivity test on the DNDC model, both grain yield and crop N uptake were significantly affected by temperature and nitrogen application rate, ammonia volatilization was significantly influenced by fertilizer N type and nitrogen application rate, N2O emission significantly affected by temperature, soil pH and soil organic carbon. More work is needed to improve the validition of DNDC model to estimate ammonia volatilization and N2O emission.