Based on the pressure-state-response(PSR)model and principal component analysis, the ecological risk assessment index system of drinking water source area was constructed, which included 6 indexes, such as pesticide fertilizer application intensity, vegetation coverage, environmental protection investment proportion to GDP, soil erosion rate, water environment self-purification capacity and soil erosion intensity. In order to construct the ecological risk assessment model of Jiangsu section of the Yangtze River, analytic hierarchy process(AHP)and expert consultation were used to determine the index weight. Taking Jiangpu-Pukou water source area of the Yangtze River as an example, using remote sensing software and geographic information system(RS/GIS)to quantify the indexes of ecological risk assessment, the ecological risk value of Jiangpu-Pukou water source area was calculated to be 0.3657, which was a lower risk degree.