［Objective］To clarify the change characteristics of nitrate export flux and pattern driven by rainfall. ［Methods］Typical subtropical hilly watershed Longyan small watershed in Hunan Province was chosen as the research object. By monitoring the dynamic changes of watershed runoff and nitrate concentration with high frequency and combining with the C-Q relationship model，the differences in nitrate export flux and patterns among different rainfall types were clarified. On this basis，the key influencing factors of nitrate export were identified by using redundancy analysis and correlation analysis.［Results］The weighted average concentration of runoff nitrate of all rainfall events varied from 0.08 to 1.50 mg/L. Among them， the weighted average concentration of light rain events was only 0.35 mg/L，and the weighted average concentrations of heavy rain and rainstorm events werre 1.68 and 2.97 times that of light rain events，respectively. The variation range of nitrate export flux in rainfall events was 4.27-353.85 g/h，among them，the average export flux of moderate rain events was only 20.39 g/h，while the average export flux of heavy rain and rainstorm events was as high as 185.08 and 194.49 g/h， respectively. In the watershed， the main nitrate export pattern was the enrichment pattern， accounting for 75%. The variability of nitrate export patterns decreased with the increase of event intensity. The results of redundancy analysis and correlation analysis showed that，compared with rainfall duration，rainfall intensity and other factors，rainfall，rainfall within three days before the event and initial discharge were the key factors affecting watershed nitrate export，and their explanatory rates for nitrate export characteristics were 33.8%，17.1% and 13.1%，respectively. Among them，rainfall was significantly positively correlated with nitrate concentration and nitrate export flux（p<0.01 and p<0.05），and rainfall within three days before the event was significantly positively correlated with the nitrate export pattern（p<0.05）.［Conclusion］The combined action of rainfall，antecedent rainfall，and initial discharge changes the source and path of nitrate transport，making nitrate export more complicated. Scientific understanding of the patterns of nitrate export driven by rainfall is of great scientific significance to guide the prevention and control of non-point source pollution in the watershed.