The invention discloses a method for measuring the geometrical dimension of an object on a conveyor belt based on binocular vision. The method comprises a step of obtaining a first planar image and asecond planar image of a target object on the conveyor belt through a binocular camera fixed relative to the position of the conveyor belt, a step of processing the first planar image and the second planar image by using a binocular vision processing algorithm and establishing a three-dimensional coordinate space of the target object, and a step of converting pixel values of object lengths in theimages into real length information according to a pre-calibrated information relationship between coordinates and image pixels and outputting the geometrical dimension information of the target object.