Abstract: A coupled atmospheric-hydrological modeling system is established over the Huaihe River Basin for predicting severe precipitation and real-time flood forecast. This system is the high-resolution regional atmospheric MC2(Canadian Mesoscale Compressible Community)model that is one-way coupled to the Xinanjiang hydrological model. The system was tested for the July 4 to 15,2005 severe flood event in real-time over the basin. The MC2 precipitation is first evaluated using observations from rain gauges over the Wangjiaba sub-region. The Xinanjiang model flood forecast is then validated with the observed hydrograph at the Wangjiaba Station. MC2 performs reasonably well in predicting severe precipitation with the forecast lead time up to 96-h. The flood forecast using MC2 precipitation shows a good result of flood timing and peak discharges at the Wangjiaba Station. The encouraging result obtained in this study demonstrates the potential of using mesoscale model precipitation for real-time flood forecast,which provides a longer flood lead time compared to many traditional methods.