Abstract: Nitrogen plays a vital role in agricultural production.With a large number of unreasonable application of fertilizer, nitrogen in the farmland has become an important factor of agricultural non-point source pollution.Loss of soil nitrogen and nitrogen farmland pay significant impact on the ecological environment.Soil Nitrogen surplus, Agricultural runoff TN, ammonium and Nitrate, can reflect different aspects of the impact of nitrogen on the environment.With the increasing amount of nitrogen fertilizer in the soil has progressively enriched with nitrogen, farmland nitrogen loss increased the risk and the number to water bodies.Nitrogen nutrient surplus witch is closely related to agricultural production is an indicator of environmental quality. With the rapid development of agriculture, an excess of nitrogen fertilizer run into the ecosystem, that become a burden on the environment. Its main earnings losses into the environment in various forms, has become an important source of non-point source pollution.Farmland nitrogen runoff loss in soluble fraction. When paddy field surface water and nitrogen concentration exceeding 30 mg/L, it will lead to the release of part of the soil mineral N, witch will lead to the release of part of the soil mineral N, increase mineral nitrogen content in soil solution.