Semi-automatic grafting machine is widely used in variety of vegetables with a low equipment price. However, its production capacity is relatively low. In order to simplify the operation and improve the efficiency of grafting, a semi-automatic grafting machine for single person to graft rootstock and scion seedlings was designed. The design of the key components of the grafting machine included stock and scion seedlings clamping and rotation mechanism, a seedling holding anti-rotation mechanism and a cutting mechanism. The seedling holding anti-rotation device adopted a double ratchet reverse stop to realize a single motor driven two axles with reverse rotation, which was used to ensure the orderly mating process for the grafting seedlings. The optimized layout design for seedling putting position, clamping, cutting, and grafting position would be convenient for single-person to put rootstock and scion seedlings at the same time. The pumpkin seedlings and loofah seedlings were used for grafting test. The different groups test of single artificial seedling was carried out to analyze the graft success rate and grafting efficiency of the model. The grafting experiments on pumpkin and loofah seedlings showed that the success rate of grafting reached 89%, which was similar to that of artificial grafting. The grafting speed reached 846.3 strains/h, which was nearly 3.3 times of artificial grafting rate. It proved that the semi-automatic grafting machine design met the requirements of factory grafting operations.