The invention provides an underwater topographic mapping and correcting method adopting an AUV (autonomous underwater vehicle) equipped with multi-beam sonar. The method comprises steps as follows: multi-beam sonar and a depth gauge are started to collect data, and each ping is corrected according to sound velocity information collected by a sound velocity section plotter; an accurate relative position between two moments is determined with a topographic matching method, so that a final navigation error of an inertial navigation system is obtained; the inertial navigation system is simplified into a spring model, a relationship between each node error and an actual final navigation error is calculated according to a stiffness coefficient formula of a spring; weight of each time node relative to the final error is determined with a topography continuity method; a final moment error is distributed to each time node. The method is independent of GPS (global position system) information in a submarine topographical map establishing process, the multi-beam sonar can be carried by the AUV for completing submarine topographic mapping of a deeper sea area, the consistency of an established map is better, the time node error is small, and the submarine topographical map can be taken as a priori topography map to be applied to the underwater topographic matching navigation.