A method for identifying sugar cane internodes was proposed based on Matlab. The cane internode was pre-processed by using gray processing and Sobel edge extraction. The mathematical morphology of expansion, corrosion and re-expansion was used to eliminate the edge of the sugar cane internode and unwanted small edge, so the edge of sugarcane internodes straight line was obtained. And then, the location coordinates of sugarcane internodes were got when R had its strongest value by using Radon function for straight line extraction. A theoretical basis of device of anti-bud injury in seedcane cutting was provided. The recognition accuracy was 100%, and the position accuracy was 0.1 mm. 