Abstract: Taishitun Town,located at the upper catchment of Miyun Reservoir,Beijing,was selected as a case study.Based on the calculation of non-point source pollution load,using the export coefficient method,economic loss caused by agricultural non-point source pollution was reckoned quantitatively,using the methodology of environmental economics.Results show that livestock breeding contributed the most to the pollution load of the area,and 53.0% to the TN and 73.9% to the TP pollution load of the town.Of the TN and TP contributions of the livestock rearing,66.5% in both was attributed to large-scaled farming.Rural area domestic pollution contributed 31.3% to the TN and 15.8% to the TP pollution load of the town.The pollution load from various land uses was the least,contributing 15.7% of the TP and 10.3% of the TN pollution load of the town.The economic loss the regional non-point source pollution caused was calculated at about 4.08 million RMB in total,of which about 40.7% was attributed to livestock breeding,ranking first,and 33.5%(of which 63.2% was caused by farming pollution) to various land uses and soil loss,ranking second.Rural area domestic pollution contributed the least to the economic loss,but 25% of the TN loss.N and P loss is the main form of non-point source pollution,accounting for 79.5% of the economic loss.The long-term impact of surface soil loss and sediment deposition cannot be neglected.

Key words: non-point source pollution, pollution loss, economic value assessment, Miyun Reservoir