In order to investigate the heavy metal pollution status of Shimu River 3 years after the suspension of mining of a pyrite mine, which is located in the upstream part of the watershed, a distributed sampling protocol was carried out along the river for water and sediment in November 2020. The samples were analyzed for Cd, Pb, As, Hg, Cu, and Zn. The single factor pollution index was calculated to evaluate the river water. The sediments were assessed by the Geo-accumulation index (I_geo) and the potential ecological risk index (RI). The results showed that the pollution of Cd in river water was more serious among the six heavy metals, and the pollution mainly occurred from the upstream branch draining the mine to the middle reaches of the river, while the pollution of other heavy metals was less or no pollution during the normal dry season. In the sediment, the average contents of heavy metals except for Hg were significantly higher than the Risk Intervention Values for Soil Contamination of Agricultural Land (GB 15618-2018) and the soil background value of Tongling. The content of the heavy metals was the highest in the middle reaches. The average values of I_geo of the six heavy metals in the sediment were Cd(3.39)>Zn(2.97)>Pb(2.49)>As(2.00)>Cu(1.93)>Hg(-0.97)，which indicated that Cd was at heavy-pollution grade. The average values of RI showed that Cd was at the very-high-risk grade, with As at high-risk, Cu and Pb at medium-risk, and Hg and Zn were at low-risk. The heavy metal content, distribution, and risk assessment of river and sediment showed that the heavy metal pollution mainly came from the mining area.