A method for measuring lens distortion, comprising: providing a test card having a dot matrix pattern of K×N dots, wherein the K and the N are both positive integer; obtaining a distorted image of the test card after being distorted by a lens; establishing a planar coordinate system for the distorted image by using a dot at an upper left corner of the distorted image as a coordinate origin, a rightward direction from the origin as a positive direction of axis X, and a downward direction from the origin as a positive direction of axis Y; positioning a center dot of the distorted image and all non-center dots by scanning and searching, and determining coordinate values of the center dot and all the non-center dots in the planar coordinate system; and calculating a distortion amount of the distorted image by using the coordinate values of the center dot and all the non-center dots according to a distortion amount calculation equation for the distorted image, thereby obtaining a distortion amount of the lens. Also disclosed is a system for measuring lens distortion. The measurement method and system accelerates the image processing speed and improves the lens distortion measurement accuracy.