In view of the problem that the grafting machine uses plastic clips to fix vulnerable seedlings and the plastic clips are difficult to recycle and pollute the planting environment, a grafting device based on UV glue coating and fixation was designed, which can automatically complete the operations of seedling clamping, synchronous cutting, butt glue spraying, seedling solidification and flexible seedling lowering. Firstly, the structural composition and working principle of the grafting device were expounded, and the key mechanisms and operating parameters such as clamping, cutting, handling, glue spraying, curing and seedling setting were designed; Secondly, in order to determine the optimal glue grafting parameters and improve the grafting success rate, taking white-seeded pumpkin (rootstock) and watermelon (scion) seedlings as the object, the atomization pressure, glue supply pressure and glue spraying distance were selected as the influencing factors, and the grafting success rate as the test index, the three-factor and three-level response surface test was carried out, and the significant ranking of the grafting success rate was as follows: atomization pressure, glue supply pressure, and dispensing distance; Finally, the Design-Expert 13 software was used to analyze the variance, respond surface and parameter optimization of the test results, and verify the test results to obtain the best parameter combination conditions. The test results showed that under the conditions of atomization pressure of 0.22MPa, glue supply pressure of 0.35MPa and spraying distance of 4.33mm, the average grafting success rate was 97.34%, the error from the theoretical value was 1.15 percentage points, and the average production efficiency was 576 plants/h, which met the quality requirements of mechanical grafting operation. The research results can provide a theoretical basis and technical support for the design and development of glue grafting robots.