The invention discloses a different-scale regional flood damage risk evaluation method. The method comprises: collecting space data of a to-be-analyzed region and attribute data associated with the space data as initial data, compressing the initial data and storing the compressed data in a created space database; standardizing the initial data, and unifying units; coupling a model by utilizing an analytic hierarchy process (AHP) method and an entropy weight method, and determining each factor combination weight; and evaluating and researching a regional flood damage risk value, classifying risk grade, and generating a flood damage risk index diagram. According to the different-scale regional flood damage risk evaluation method, by utilizing the collected natural and social data as input and various algorithm coupling models, the weights are determined, and finally the flood risk grade evaluation index diagram is generated; therefore, the accuracy of flood damage risk evaluation is improved, objective and efficient advantages are achieved, and the flood damage risks, which have possibility of occurring in a research region, under given conditions are further intuitively shown.