In order to analyze the response of rainfall-runoff process to spatial distribution of impervious area, a hypothetical experiment area of 3 km×3 km was constructed, and 36 kinds of spatial distributions of impervious area with six impervious rates were set. Numerical experimental models were established to simulate the rainfall runoff process under six kinds of short-duration design rainfall with different return periods of 2,5, 10,20, 50, and 100 years. Based on the simulation results, the runoff processes under different rainfall conditions and spatial distributions of impervious area were analyzed. The results show that, under the same impervious rate, the difference of runoff coefficient under different spatial distributions of impervious area is generally small, and the spatial distribution of impervious area has a certain influence on the peak runoff and time to peak runoff. Under the same rainfall condition, the change in impervious rate is the dominant factor for the alternation of the runoff process, and there exists a linear relationship between the runoff coefficient and impervious rate. With the increasing of impervious rate, the runoff process line gradually changes from “low and fat” to “sharp and thin”. Keywords: impervious area; spatial distribution; impervious rate; rainfall runoff; numerical experiment