Soil nitrogen loss caused by slope runoff is one of the important source of agricultural non-point source pollution. In order to investigate the effects of slope length (2 m, 3 m, 4 m, 5 m) and rainfall intensity (0.65 mm/min, 0.69 mm/min, 0.83 mm/min, 0.85 mm/min, 1.01 mm/min, 1.20 mm/min, 1.37 mm/min, 1.54 mm/min, 1.68 mm/min, 1.80 mm/min) on runoff producing processes and nitrogen loss, an artificial simulated rainfall experiment was conducted. The results showed that: (1) Under the condition of rainfall, the changing trends of different forms nitrogen concentration in runoff were high in early stage, then reduced with increasing time, and slowed down at 20 min, and gradually became stable for the final rainfall, and in the end they tended to coincide; (2) Under the same slope length, the loss content of different forms nitrogen increased with increasing rainfall intensity, showing a significant positive correlation. In each rainfall events, the loss of different forms of nitrogen was always the maximal when the slope length was 5 m, and the minimal when the slope length was 2 m; (3) There were very significant correlations between runoff volume and total loss of TN and NO3-—N, but the influence on NH4+—N was weak; (4) The correlation between total loss of TN, NO3-—N and slope length, rainfall intensity, runoff volume were very significant, and the significance of the correlation followed the order of runoff volume＞rainfall intensity＞slope length. However, the total loss of NH4+-N was significant correlated with rainfall intensity only; (5) The influence of slope length, rainfall intensity or runoff volume to the total loss of different forms nitrogen in the runoff could be described as linear correlation equations, and the significance level was in order of TN>NO3-—N>NH4+—N.