In order to meet the requirement of non point source pollution load calculation in the Feilaixia watershed, the SWAT runoff model was used to simulate the daily runoff process in the study area from 1969 to 2011. Based on the hydrological, meteorological, terrain, land use data and soil types of the Feilaixia watershed, the SWAT runoff model was constructed. The 14 runoff parameters were calibrated by SUFI-2 method in SWAT-CUP, and their sensitivities were analyzed too. The quantitative evaluation of the runoff simulation effect was carried out.The results showed that the parameters which have significant influence on the runoff process included CN2, CH_N2, GW_DELAY, SURLAG and so on. In the daily runoff process, Nash-Sutcliffe coefficients were both up to 0.83 in the calibration and the verification period, and the relative errors were 1.40% and 0.58%. The simulation results obtained a smaller uncertainty as most of the simulated value lay on the uncertainty interval, indicating that the constructed SWAT runoff model has excellent accuracy and high applicability to the Feilaixiawatershed.