Taking Tunxi watershed in the upper of Xin'an river as study area,the paper built the database of SWAT model about weather, soil, land use and crop management.Based on the monthly observed runoff, sediment loads and dissolved nitrogen load data from 2000 to 2010, it carried out calibration and validation of multi-parameters, and multi-site .It evaluated the applicability and reliability of SWAT model in Tunxi watershed basin by use of multi-objective, Nash-Suttclife efficiency, linearly dependent coefficient and relative error. The results showed that the simulation of runoff is very good. The simulation results on sediment and nutrients salt are desirable. The model has good adaptability and may analyzed the non-point pollution problems in Xin'an river basin.The constructed database and calibrated parameters can provide a reliable scientific basis and decision support for the further water environmental management in the basin.