Abstract: Based on data from GIS information, meteorological stations and hydrological stations, the applicability study of risk precipitation in Datong river basin was carried out using SWAT model, HBV model and statistical model. The results indicated that, the middle rain and above the middle rain in Datong river mainly appeared from May to September, the cumulative number of times was 41 from 2007 to 2011, and the trend of frequency and intensity showed an obvious increasing. Through the results of the application of three models in Datong river basin and the test of the actual flood,the SWAT model was the best method to modify the runoff in the Datong river basin, with efficiency coefficient of 0.87 and R² of 0.94 during the validation period, and with efficiency coefficient of 0.62 and R² of 0.83 during the calibration period, and simulating runoff and observed runoff reached the testing standard; The coefficients of determination and NSE were 0.84 and 0.61 during the validation period with HBV model , but they were 0.81 and 0.51 during the calibration period, there was no good fitting rate using HBV model compared with SWAT model. If there is a long period of hydrological data in the basin, it is more scientific to use hydrological model to determine the critical rainfall. However, the statistical model, based on the regression relationship between precipitation and water level difference, does not consider the process of surface runoff formed from rainfall, so the threshold value determined is too large.

Key words: small and medium-sized river, hydrological model, risk precipitation, Datong river basin