Pollution source tracing is the basis for the protection and management of the environment. Taking the advantage of remote sensing for its simultaneous monitoring, we traced the pollution source in Shedugang River, a major inflow river of Taihu Lake. It is shown that the pollution sources in Shedugang River are concentrated to certain areas. Transversely, the concentration of TN, TP, NH3—N and CODMn of the neighboring fish ponds are obviously higher than that in Shedugang River. Along the river channel, the water quality indices in the water bodies of industrial and residential areas, which are strongly affected by human activities, are remarkably higher than those of agricultural areas, showing the potential effect of human activities on the water quality of the river channel. According to the remote sensing results, there is a large number of fish ponds scattered along the west coast of Taihu Lake. Limited by the monitoring time, we did not find the discharge of waste water from fish ponds to the river; however, highly polluted fish pond water is a potential pollution source once discharged into river.