Abstract: There is much error in flood forecasting process due to the limited model and the inadequate real time information, however,it is an effective method based on the hydrograph interactive technology to reduce the forecasting error. This paper introduces the significance of the interactive correct technology applied to forecasting hydrograph,and the process fit smooth ness and the cubic interpolation technology Based on the technology above,it can be realized to correct the forecasting hydrograph interactively in the form of elastic which is applied to the flood forecasting system. The case study indicates that the technology can be used easily to improve effectively the accuracy of flood forecasting.