To investigate the solutions to the problems of severe groundwater over-extraction and mixed and variable runoff generation mechanisms(alternating dominance of the saturation-excess and infiltration-excess runoff generation with time and space)in North China, based on the distributed TOKASIDE model, a distributed spatial dynamic combination hydrological model(TOKASIDE-D)was established by dynamically identifying the saturation-excess and infiltration-excess runoff generation grids through the relationship determination between precipitation and soil water content. The Beixindian Watershed in North China is selected for the validation and the analysis. The results show that compared with the original model, the flood simulation accuracy of TOKASIDE-D model in the Beixindian Watershed is improved significantly, the qualified rate of runoff depth error is increased from 44% to 56%, and the qualified rate of flood peak error is increased from 44% to 78%. TOKASIDE-D model can accurately capture the control effect of rainfall, soil moisture and other dynamic factors on the runoff generation mode.