Nitrogen loss in non-point source is the main factor causing water pollution. By dynamic monito-ring of water body nitrogen in six ditches and stream channels in Baoxiang River watershed , the characteris-tics and influence factors of nitrogen pollution in water body were studied. Results showed that in different locations and different times,the nitrogen concentration of ditch water on farmland is greatly different from that in channel water. The average concentration of total nitrogen (TN) in ditch water is higher than that in the corresponding channel water. The average TN concentration in ditch water ranged from 3. 86 to 22. 86 mg/ L and the TN concentration in channel water,from 3.14 to 6.63 mg/ L. The overall trend is that the ni-trogen concentration of water body gradually increased from upstream to downstream. Nitrogen in ditch water on farmland and in channel water showed the same trend over time. TN between ditch water and channel water and TN between ditch water on farmland and the surface soils surrounding ditches and stream sediment are significantly correlated