Abstract: A detection method has been introduced for cathay hickory grade based on machine vision in this paper. On the basis of adequate understanding of cathay hickory shape, its digital images were obtained using CCD camera. The width, length and weight of the fruit were extracted through mathematical morphology method. According to these characteristics, the mathematical model was established. The weight for each characteristic was endowed based on some suggestions of jobholders. Comprehensive evaluation standard for cathay hickory grade was established. It was demonstrated that the classification method was objective and reasonable, and the classification results were more accord with peoples consumer psychology and visual habit．

Key words: machine vision, cathay hickory, classification, image processing