Abstract: In order to study the impact of mining on river ecological environment in the Baiyinnuoer lead-zinc mining area, 6 river sediment samples were collected from upstream to downstream, and pH, LOI, particle size and the total amount and chemical form of As, Cu, Pb, Zn and Cd were measured. The test results show that tailings pond 1 is the main cause of significant increase in contents of heavy metals such as Pb, Zn and Cd in the sediments. The correlation coefficient between heavy metals in sediments and coarse silts (16-63 μm) is 0.79-0.95, indicating that heavy metals tend to be concentrated in coarse silts, while pH and organic matter in sediments have no significant influence on the total amount of heavy metals. As and Pb in sediments are mainly in the residual form and Fe-Mn oxides bound, accounting for 78.82 % to 89.87 % and 36.96 % to 78.20 % respectively. Cu and Zn are mainly in the residual form, strong organic bound and Fe-Mn oxides bound, accounting for 76.38 % to 85.96 % and 74.94 % to 90.34 %, respectively. Cd is dominated by ion-exchangeable form, carbonate bounded form and strong organic bound, accounting for 51.15% to 79.53% of the total, while ion-exchangeable Cd accounts for 5.72% to 49.63% of the total. Therefore, Cd poses the greatest potential threat to the river ecological environment. The correlation coefficient between ion-exchangeable Cd and pH of the sediments is -0.813, which shows a relatively strong negative correlation. The content of the ion-exchangeable Cd decreases from 33.44% to 5.72% while pH of the sediments changes from weak acidity to weak alkalinity. The results of this study are of important reference significance for the restoration and treatment of ecological environment in the Baiyinnuoer lead-zinc mining area.