Rainfall and the concentrations and variations of total nitrogen (TN), nitrate, nitrite and N transformation in the headwater area of Taizi River watershed were studied by filed monitoring. Results showed that:(1) Rainfall from May to September in the watershed accounted for 81.8% of the total annual rainfall, which is the principal period for non-point source nitrogen output. (2) The mean concentration of TN had a waving trend in different monitoring sites. The landuse types, in order of decreasing TN content, were chicken farm, village, dry land and woodland, which was consistent with the soil background value. (3) From May 7th to June 10th, the early rainfall after a long term drought increased the TN content in dry land, village and chicken farm in comparison with rainy season. From June 10th to September 30th, TN content firstly decreased and then increased due to the increases in rainfall amount and frequency. In addition, the interaction of extraction and dilution caused by rainfall also increased the TN content. (4) The concentrations of nitrate and nitrite nitrogen in each site had a significant positive correlation with rainfall amount (p<0.05). Nitrate was the main form of total nitrogen output and accounted for about 69.2%, 63.4%, 61.4% and 63.8% of TN for woodland, dry land, village and chicken farm, respectively. Although vegetation cover had benefits in reducing soil erosion and the loss of TN, it increased the loss of soil soluble nitrogen.