The impact of mining on environment should get more attention. The Chaobai River is the major source of Miyun Reservoir, a unique surface drinking water storage for Beijing. 11 sampling sites along the Baihe and Chaohe rivers are chosen in June and September 2012 to investigate the distribution, pollution and sources of trace metals in suspended particulate matter. We analyzed 10 trace metals and Sr, as an indicated element of soil weathering. 7 samples of colloidal particles were collected and the characterization of colloids was performed using Transmission electron microscope. The results reveal that most of mean concentrations of metals in suspended particulate matter are higher than the background of Beijing soil and have no significant difference in both seasons. According to the results, a serious contamination with Cd should be discussed and addressed, especially at site B4 on Baihe River close to the gold mine. Statistical analysis suggests that Zn, Pb, Cd and Sb represent anthropogenic sources including industrial mining, atmospheric depositions and vehicle emissions; the Ni, Cu and Ba pollution may have mixed sources of anthropogenic and natural origin. The partitioning coefficient of metals shows that most metals are affected by mines, with the exception of Ni, Cr, Cu and V, which were not significantly affected by gold mine. The source of Cd included mining pollution and other serious Cd pollution sources. The colloidal particles in rivers played important role in trace metals transportation. In this study, iron oxides, organic matter and amorphous clay minerals were important in the removing and transformation of trace metals in water. In conclusion, the analysis and assessment of particulate metals would help control and reduce the pollution of trace metals in Chaobai River and Miyun Reservoir, and consequently contribute to preservation of public health.