Yongsan ward is located at central place connecting south and north ecology axis of seoul. Various environment-friendly Yongsan development could pose positive effects on NPS(non pollutant source) pollutant reductions and water quality improvement at Han-rive because BOD, T-N, and T-P NPS discharges took 90% of total pollutant from this area. In this study, direct runoff and NPS pollutant loads were evaluated before and after development using spatio-tamporal change in CN(curve number) and EMC(event mean concentration) data. It was found that direct runoff value is $23,584,724m^3$, and BOD, T-N and T-P loads are 104,456 kg/year, 111,483 kg/year and 7,500 kg/year under pre-development condition, respectively. Annual runoff, BOD, T-N and T-P reducing rate were 12.9%, 33.3%, 35.6% and 40.7% under integrated post-development condition, respectively. Based on the results obtained in this study, environment-friendly urban development could be achieved at Yongsan area.