Abstract: Abstract: At present, vegetable grafting techniques are extensively studied in the world, including Japan, South Korea, China and North America, and various types of grafting machines have been successfully developed. In China, Zhang Tiezhong, Gu Song and other researchers carried out the research work on cut-pasted grafting method in vegetable grafting machines. However, due to the complexity of grafting technology and the poor applicability of grafting machine, these machines are not widely used in China. Therefore, it is significant to develop the automatic grafting machine that can be suitable for agricultural production in Northeast China. In order to realize the automation of vegetable grafting machine, and solve the problem of low survival rate after cutting, the cutting device for muskmelon automatic grafting machine was designed and the working parameters of the device were optimized by using experimental methods in this study. A set of economical and suitable grafting machine was designed, which not only reduced the cost of design, but also ensured the efficiency and quality of the work. By rotating the cylinder to cut grafted seedling, the action was accurate and rapid, and at the same time effectively avoided the problem of the damage to the seedling during the cutting process. In the whole process, the device was stable, and the blade could be replaced only on a regular basis. The cutting efficiency was obviously improved. For the rotary cylinder cutting parts, the volume was very small, and the price was also relatively low. The whole set of equipment could be assembled and debugged under the existing conditions of the laboratory, and the design of the structure was simple and compact, which was easy to operate. In the case of ensuring the efficiency and quality of the work, the production cost of the equipment was successfully reduced. It is suitable to be popularized widely in China. The grafting seedlings for the typical muskmelon were selected as the research objects. Three variables were selected as the experimental factors, i.e. cutting angle, cutting radius and cutting height. Grafting fitting percentage of rootstock and scion was determined as the experimental index. Moreover, the single factor experiment and the quadratic regressive orthogonal experiment were conducted in order to determine the optimal technological parameters of cutting device. The single factor experiments studied the influence of cutting angle, cutting radius and cutting height on variation coefficient of cutting, respectively. According to the results of single factor experiments, the quadratic regressive orthogonal experiment was conducted, which selected 2 reasonable values within effective range as 2 levels. The optimal operating parameters of cutting device for muskmelon automatic grafting were determined by the experiment. For the cutting device, the optimized cutting angle was -9o, the optimized cutting radius was 39 mm and the optimized cutting height was 30 mm, and the grafting fitting percentage of rootstock and scion was 98%. The optimized parameters were proved to bring about the best cutting performance and meet the requirement of grafting survival rate. Under the conditions of the optimal operating parameters, the cutting device of muskmelon automatic grafting machine can meet the requirements of the design. Therefore, the cutting device can achieve automatic cutting, and the experimental results provide the important reference for developing vegetable automatic grafting machine.