Abstract: Taking the typical farmland ecosystem of Changwu Demonstration Area in the south of Loess Plateau as the study object,based on the using of DNDC(Denitrification-decomposition) model,the carbon and nitrogen cycling characteristics of wheat field ecosystem in four different dealing through successive six years were analyzed.And also by comparing with known experimental results and practical measuring data.it was preliminarily verified that the model was applicable.On the basis of these,the main managements for agricultural development in the future were proposed in the area.