This study aims to analyze the situation and behavioral characteristic of nonpoint pollution sources by examining and analyzing the basic data such as the hydraulic and hydrologic characteristics and land use situation of the basin, and provide basic design data for basin management by calculating the soil loss rate due to rainfall effluents, for the Golji Stream basin located at Jeongseon, Gangwon province. For this, this study applied the SWAT model to the object basin, established input data for the model through parameter estimation and sensitivity analysis, and conducted a simulation. This study confirmed the suitability of the model by conducting a verification with the actually measured spillage being the basic of simulation results, analyzed that the maintenance of the sub-basin #15 with 34644.37 ton/yr of soil loss rate calculated by sub-basins in the object basin should be conducted first, and showed that there happened about 14,800 times of difference from the sub-basin #1 with 2.33 ton/yr of soil loss rate, the lowest. It is judged that this result should be considered as very important to set the priority order of basin management in a large basin and should be considered reasonably when applied to the work.