Hebei Flood model is a conceptual hydrological model with both storage-excess runoff and infiltration-excess runoff mechanisms. In order to investigate the application effects of Hebei Flood model in semi-arid areas and of objective function on the simulation results, in this paper 10 floods were simulated from 1994 to 2010 based on Hebei Flood model for the study area which located in the upstream of the Yellow River areas. The effects of different objective functions (by using the peak-weighted root mean square error, weighted error and efficiency coefficient, respectively) on the simulation results were studied. The results showed that: Hebei Flood model has good applicability to simulate the flood process in the semi-arid areas of northwest China, the effects of different objective functions on the simulation results of the model have different emphases, but the simulation results were very close, so in practical respects, the objective function should be selected considering the appropriate focus of attention to avoid certain blindness, when the peak-weighted root mean square error was chosen as the objective function, the simulation of the secondary peak was better.