The invention discloses a car brake pad surface defect detecting and automatic sorting system based on machine vision. The system comprises a machine vision system. The machine vision system comprisesa camera, a camera lens and a light source. The machine vision system is connected to a CPU. The CPU is connected with an upper computer and a sorting arm. The upper computer involves image preprocessing, image segmentation, feature extraction and mode recognition, mode recognition involves color recognition, shape recognition, texture recognition and multi-feature fusion recognition, the machinevision system detects a to-be-sorted target image and transfers information to the CPU, and the CPU processes the received information. The car brake pad surface defect detecting and automatic sorting system based on machine vision is reasonable in design, brake pads are conveniently detected through image acquisition, processing and recognition, the sorting arm is controlled to act by means of detecting results, brake pads with detects are sorted to an unqualified area, qualified products leave a factory, the purpose of automatic sorting is achieved, and using is facilitated.