For grafting brings various advantages to plants, such as enhancing the disease resistance, speeding the growth, increasing production of per unit and reducing chemical application, it is a crucial step in large-scale vegetable production. Furthermore, automatic grafting by machine can effectively improve the survival rate of grafted seedlings and the working efficiency, which makes this kind of technology a rigid demand in vegetables’ commercial production. At present, global research within the field of automatic grafting and related robotic technologies has been carried out for years. The recent developments and the key technologies were systematically analyzed based on studying information in both academic and commercial fields. And five kinds of key technologies were brought forward, which were seeding mechanical grabbing technology, seeding romanticized delivering technology, stock/scion cutting technology, stock/scion joining technology and controlling technology for the grafting system. Moreover, the conclusion and prospection for the worldwide automatic grafting technologies were provided from three aspects: firstly, the level of the automation for grafting machines would make a further progress in the near future; secondly, the amount of the plants that a single grafting machine can process was supposed to increase; thirdly, the state of the art technologies in relationed fields, such as agronomy, ergonomie and artificial intelligence, would promote the grafting machines’ performance more in the future.