In order to solve the problem of scion seeding difficult to clamp in traditional vegetable grafting machine and easily be injured, an air-suction mechanism was developed with vacuum suction head adsorption for scion, which based on the analysis of structural parameters and mechanical properties of suction seeding. A computational fluid dynamic (CFD) simulation of a 3-D model was developed in the given boundary conditions to investigate the fluid flow features and the effect of adsorption ability caused by various factors. The orthogonal test was adopted in this experiment to optimize the design of the structure of the vacuum suction head. The result showed that the important sequence was determined as follows: shape of the suction head, vacuum degree and the depth of counterboring. Experiment results showed that the feature of the proposed air-suction mechanism was safe and reliable. The success rate of the proposed scion clamping mechanism reached to 97.8%, no scion wan injured, and the success rate of insert into stocks reached to 85.6%. Thus, it indicated that the proposed scion clamping mechanism could satisfy the requirements of location and clamping for vegetable grafting. 