The invention belongs to the field of machine vision and detection, and discloses a vision-based identification and locating method for outer beam holes in a multilayer beam. The method comprises the steps of (a) calculating a conversion coefficient for converting an actual size into a pixel size; (b) selecting a generation template in a to-be-identified outer beam hole of the multilayer beam, performing template matching on a to-be-identified image, obtaining a size type of the hole, intercepting a new local image by taking an optimal matching point as a center, and performing sub-pixel precision-level edge detection on the new image; and (c) fitting central coordinates of the hole by using edge point data, and performing multiplication by the conversion coefficient to obtain the central coordinates of the to-be-identified outer beam hole of the multilayer beam, thereby realizing the identification and locating of the hole. Through the method, automatic blind hole identification and locating of the outer beam holes in the multilayer beam are realized, the labor intensity of workers is reduced, the machining precision of the outer beam holes and the riveting quality of the multilayer beam are improved, and the production efficiency is improved by multiple times.