Abstract: LH-OAT analysis module and SCE-UA auto calibration module have been added to SWAT 2005.During the process of parameter sensitivity analysis and calibration,the computing time increases with the number of subbasins.For a watershed with an area of 16800 km2,subbasins of 138 for Beijing,the time is about 1 minute for a 5 yeas simulation of SWAT model.Because the parameters auto calibration program of SWAT model tries many times of different parameters,the model was rerun about 5000 times for 10 parameters used in Beijing,which will cost about 4 days.If any mistake occurs in this process,it will need to redo the calibration work.Therefore this calibration method is ill-suited and unacceptable for large basins.An idea is put forwarded and realized in the paper,that is we can only simulation some subbasins,such as the only subbasins flow to target hydro station.Then with only simulation of these several subbasins,the time used for parameters auto calibration will be greatly reduced.With this method applied in parameter calibration in Beijing Swat model,it takes no more than 30 minutes to calibrate the five years' day runoff of Qianxinzhuang hydro station and the results are preferably.The calibration of runoff process for a number of hydro stations in distributed hydrological model can be rapidly done through the generalization of this method.

Key words: LH-OAT sensitivity analysis, SCE-UA parameter estimation, SWAT