In order to satisfy the demand of Sanxia Dam irrigation works construction,the research on rainfall forecast for the Dam region was conducted.The strong rainfall process in Sanxia Dam region was analysed and some relative statistics laws were summarized.On this basis a 6—12 hours synthesis forecast method for strong rainfall process was obtained by utilizing numerical products of rainfall prediction from Japan,satellite pictures,radar data and synoptic experience.The experiment in 1999 shows that the method is effective certainly for forecasting the strong rainfall process which affected the Dam region.