Abstract: Continuous water environment monitoring was conducted at six representative monitoring sites in 2023 in the Qingshui River, a tributary of the Yongding River, to analyze the spatial and temporal distribution characteristics of nitrogen, phosphorus and other substances during the river snowmelt season. The primary water environmental indicators measured included total nitrogen (TN), nitrate nitrogen ( \textNO_\text3^- -N), nitrite nitrogen ( \textN\textO_\text2^- -N), ammonia nitrogen ( \textNH_\text4^\text+ -N), total organic nitrogen (TON), total phosphorus (TP), total dissolved phosphorus (TDP), particulate phosphorus (PP), chemical oxygen demand (COD), and total suspended solids (TSS). The findings indicated that the proportion of nitrogen-based nutrients in rivers exhibited distinct seasonal variations. During the snow melting period, the average TON concentration in runoff constituted 69% of the TN concentration, with the average proportions of \textNO_\text3^- -N, \textNH_\text4^\text+ -N, and \textN\textO_\text2^- -N at 28%, 2%, and 0.46%, respectively. During the snow melting phase, the TON concentration increased along the river's flow, whereas the \textNO_\text3^- -N concentration gradually decreased. However, upon entering the level period, this pattern reversed, revealing a gradual increase in the \mathrm \textNO_\text3^- -N concentration and a concomitant reduction in the TON concentration as the river progresses. The concentration of phosphorus substances varied significantly during the snow melting period, with an average peak-to-trough ratio of 5.9, and a maximum increase of up to 14.0 folds. The peak concentration across all sections complied with the Class Ⅲ standard of Environmental Quality Standards for Surface Water (GB 3838-2002). The concentration of COD during snow melting increased by as much as 213.6%. During the early stage of snow melting, the peak concentration of all sections, excluding Chongli South Section, exceeded the Class Ⅲ standard and had high COD values that persisted for approximately two weeks; during the late snow melting period, the COD values decreased and could comply with the Class Ⅲ standard. During the early stage of snow melting, the discharge and utilization of stored winter pollutants were the primary factors causing the concentration fluctuations of various substances; during the intermediate and later stages of snow melting, temperature predominantly influenced the concentration variations of N-containing substances, whereas water production process influenced the concentrations of COD and phosphorus.