At 14:00 BT 18 June 2017, a flash flood happened in the Shiyanggou Watershed of Mentougou District, Beijing, causing casualties. The station precipitation, combined precipitation of station and satellite, radar precipitation and satellite precipitation are used to drive the WRF-Hydro hydrological model to evaluate the performance of these different precipitation data in the flash flood simulation. The results show that the spatial distribution and temporal variation of these data are similar. Except radar precipitation, other precipitation data underestimate the precipitation. In these flash flood simulation experiments, the flash flood simulated by radar precipitation is most similar to the actual flash flood in terms of occurrence time and peak flow. The flash floods simulated based on other precipitation data are close to the actual streamflow in terms of occurrence time but the peak flow is underestimated. At present, conventional precipitation products by routine observation stations can not meet the requirements of research and early warning of small-scale abrupt flash floods. So, it is urgent to integrate radar and satellite precipitation products with observation station precipitation to get real-time high-resolution precipitation products.