High concentration of nitrogen is one of the important factors affecting the river water environment. This paper aims to gain insight into the spatiotemporal variation characteristics of TN concentration in the Luan River Basin. Based on TN concentration monitoring data during 2018 and 2022 in the Luan River Basin, this paper applied spatial cluster analysis, divided the basin into source, upstream and downstream area, to carry out the study on the spatiotemporal distribution characteristics and variation of TN concentration. The influencing factors of TN concentration change was elaborated through exploring the relationship of TN concentration to precipitation, runoff and groundwater level. The results showed that: (1) TN concentration in the source area maintained at about 1.86mg/L, with a relatively low level; The TN nitrogen concentration in the upstream area is highest, with the highest concentration exceeding 10mg/L, which is closely related to the region’s population concentration, Livestock and poultry farming, and agricultural surface pollution; The downstream was regulated by the Panjiakou-Daheiting Reservoir, and the TN concentration stabilized at about 5 mg/L. (2) The concentration of TN in Luan River was significantly affected by precipitation. When the monthly precipitation was less than 250 mm, TN concentration was strongly negatively correlated with precipitation, showing a trend of TN concentration decreasing with the increase of precipitation. When the monthly precipitation is greater than 250 mm, the nitrogen in the soil is washed and released, and the TN concentration increases with the increase of precipitation. (3) The regulating role of the Panjiakou-Daheiting Reservoir was significantly affect the reservoir downstream TN concentration. Large releases from reservoirs can greatly increase river runoff, this leads to the release of nitrogen from the sediment, and increases the river TN concentration. (4) The hilly area of the Luan River Basin has large undulations and shallow groundwater table Surface water is recharged laterally by groundwater during dry periods, This causes the surface water NO3-
-N concentration increase and leads to an increase in TN concentration. The study indicated that the TN concentration in Luan River Basin showed upstream> downstream> source area; The precipitation and the regulating role of the reservoir had a significant effect on TN concentration; Groundwater recharge of surface water during dry periods in hilly areas is one of the reasons for the increase in TN concentration.