This invention discloses an automatic magnetic core sorting system based on machine vision, which comprises an image acquisition and detection mechanism, a digital conversion module, an image processing module, and a workpiece sorting mechanism. The digital conversion module communicates with the image acquisition and detection mechanism. The image processing module receives the digital signals of images of each workpiece taken from various angles and compares the digital signals with a preset value. Afterwards, the results of comparison are sent to the central control module which judges and controls the operations of the workpiece sorting mechanism according to the results sent from the image processing module. This invention adopts the machine vision-based automatic identification technology to automatically identify color and appearance defects of magnetic sheets on conveyor line. With advantages of real-time and accurate detection with high precision, it greatly improves the efficiency and the degree of automation of production.