Abstract: Fengjiajiang river is an important ecological corridor of Beihai town. It is of great importance in understanding the pollution level of Nitrogen and the control and prevention of Nitrogen pollution in Fengjiajiang river, through the investigation of Nitrogen spatial distribution characteristics, pollution sources and influence factors. The spatial distribution characteristics of Nitrogen in the surface water and groundwater were analyzed with geostatistical method. The results show that the Nitrogen concentration in the surface water has the characteristics of high NH₃-N and low NO₃-N, with the average value of NH₃-N 5.42 mg/L. NO₃-N is concentrated in the pore groundwater, with the maximun value of 32.63 mg/L. The main sources of Nitrogen pollution include domestic pollutants, animal and human manure and the usage of chemical fertilizer. The important factors affecting the migration and transformation of Nitrogen pollutants in the water boby of the study area are pH value, redox conditions, lithologic structure and thickness of the unsaturated zone.