Abstract: As the water source of the Middle Route of South-to-North Water Diversion Project, the water quality safety of the Danjiangkou Reservoir Area is crucial. The flood season is a main period when pollutants concentrate in reservoirs, posing significant challenges to water quality management and ecological security in the reservoir area. Total nitrogen is one of the important indicators reflecting the water quality in the reservoir area, and it is also a key factor measuring non-point source pollution and eutrophication. Based on the hydrological monitoring data of the Danjiangkou Reservoir Area during the flood period in July 2024, combined with hydrological conditions and watershed characteristics, this study systematically analyzed the temporal evolution, spatial distribution, and inflow and outflow flux characteristics of total nitrogen. The results showed that during the tracking-monitoring period, the average total nitrogen concentration during the flood period in each section (2.23 mg/L) was higher than that during the start-up period (2.01 mg/L) and the exit period (1.97 mg/L), and the total nitrogen concentration in the Han part of the reservoir was significantly higher than that in the Dan part of the reservoir. The input from the Hanjiang River main stream accounted for 62.9% of the total nitrogen inflow flux of the reservoir area, while it accounted for 84.5% of the total nitrogen outflow flux of the reservoir, indicating the inflow total nitrogen flux was significantly higher than the outflow, with a retention rate of 75.6%. Rivers with high inflow flux per unit area were more likely to have smaller runoff. During the tracking-monitoring period, the total nitrogen concentration in the inflow control section was 1.1~3.2 times that of regular monitoring. During the research period, the total nitrogen concentration in the reservoir area remained stable and was limited by the impact of flood periods, indicating that the reservoir area had a good adjustable capacity. The reservoir area had a significant concentration effect on spatial regulation and transport process of total nitrogen, and a high concentration of total nitrogen input was the key factor for high total nitrogen inflow flux. This study can provide a scientific basis for water quality protection and pollution prevention and control in the Danjiangkou Reservoir Area.