The invention belongs to the technical field of water circulation of water conservancy projects and particularly relates to a distributed-type river basin water deficit calculating method based on terrain and soil characteristics. The method comprises the following steps: step1, processing basic data of an underlying surface of a river basin; step 2, counting grid terrain indices within basin perimeters; step 3, calculating soil characteristic parameters within the basin perimeters; step 4, quantitatively expressing distribution of river basin water deficit; and step 5, drawing cumulative distribution curves of river basin water deficit to acquire a calculating model of distributed-type river basin water deficit. when being applied to real-time flood forecasting, The distributed-type river basin water deficit calculating method based on the terrain and soil characteristics can substantially improve accuracy of flood forecasting and provide reliable scientific support for river basin flood-prevention early warning and the like. The distributed-type river basin water deficit calculating method based on the terrain and soil characteristics is not only suitable for a lumped-type hydrological model but also suitable for a distributed-type hydrological model and can effectively promote in-depth development of river basin hydrology science research.