Abstract: The using of automatic grafting machine can speed up the breeding of excellent tree species. The cutting mechanism of root stork is an important subsystem of automatic grafting machine. To achieve the goal that root stork can be cut automatically, a cutting mechanism of root stock was designed, which can complete the align, lock, cutter and retracting automatically. The work flow of the mechanism was analyzed; the parameters of this mechanism were confirmed. The experiment has show that the cutting mechanism can accomplish the cutting of root stock with great efficiency and speed.