Using an ensemble forecast product from the European Centre for Medium-Range Weather Forecasts(ECMWF)with a ten-day lead time, forecast data in the Jiangjiaji Catchment of the Huaihe River Basin were extracted and disaggregated to drive a flood forecast model to simulate a flood event in August 2008. In order to study the effect of the flood forecast model driven by the ECMWF ensemble data, the simulated results from this model and the results from a model driven simply by the field precipitation data were compared and analyzed. The results show that the flood forecasting accuracy was improved using the ECMWF ensemble forecasts, and the lead time was extended 48 h. The forecasted discharge hydrographs can provide the uncertainty range of forecast discharges, which provides a scientific decision basis for flood control and disaster mitigation.