Abstract: The physically-based distributed hydrologic model（ GSSHA model）develops a one-dimensional Richards’ infiltration equation based on saturated or unsaturated zone to describe the soil water infiltration process. Richards’ equation is more accurate in describing soil water movement. However, a large number of parameters lead to certain difficulties in practical applications. In this paper, the sensitivity of the eight parameters, which have clear physical meaning and significant influence on runoff and concentration calculation in GSSHA model, is analyzed. The control variable method is used to simulate and compare with about ten different values of single parameter. The ratio or difference between simulated maximum values and minimum values of peak discharge and peak time is used as a criterion to judge sensitive parameters. Then the sensitive parameters of peak discharge and peak time are selected and sorted. Huangjiahe watershed in the southern part of Ningxia is selected as the research area. 18 flood events from 2000 to 2015 are simulated, of which the first 13 events are calibration period and the rest of 5 events are validation period. The application effect of GSSHA model in semi-arid areas is studied with the parameters calibrated based on the principle of runoff depth first and peak discharge then. The result of parameter sensitivity analysis show that the saturated hydraulic conductivity, bubbling pressure, and initial soil moisture are the highest sensitivity to peak discharge, and these three parameters are also the parameters with the highest sensitivity to peak time. GSSHA model has high simulation accuracy for the flood events in Huangjiahe watershed in both calibration period and validation period. The relative error for runoff depth, the relative error for peak discharge, the relative error for peak time, and Nash efficiency coefficient in the calibration period are 3.51%, 10.84%,-0.77 and 0.80, the values in the validation period are 2.18%,-6.98, 0 and 0.79.