The present disclosure provides a method for training a document image distortion correction model, the method being performed by at least one processor. This method includes receiving a first grid dividing a document area into multiple cells on a first image comprising the document area, based the first grid, generating a second grid representing a state in which a distortion of the first image is corrected, generating a backward map calculating a pixel in the first grid corresponding to each pixel in the second grid, and training a document image distortion correction model to generate the backward map from the first image.