Abstract: Abstract: The grafting and cultivation of Cucurbitaceous vegetables are characterized by the strong root system, heat resistance, disease resistance and good absorbing ability for soil fertility. Oblique grafting is a common method for Cucurbitaceous vegetables. The pressing and clamping of the stock cotyledons is one of the important issues to be considered in the design of oblique inserted grafting machine. According to the problem that the existing Cucurbitaceous vegetable grafting machine easy to break the petiole of cotyledons or damage the cotyledons in the process of cotyledons pressing, the stock cotyledons pressing and clamping mechanism used in Cucurbitaceous vegetable grafting was designed and developed by measuring the characteristic parameters of the cotyledons and by adding an imitation blocks on the cross clamp mechanism designed by the author before to adapt to the morphological characteristics of the stock cotyledons. The shape of the imitation blocks in the pressing and clamping mechanism was close to the natural shape of the cotyledons in order to prevent the breaking of the cotyledon. In the process of pressing the cotyledon, the pressing roll of the pressing and clamping mechanism could automatically slip on the imitation blocks to realize the automatic adjustment of the compression force and to avoid the damage of cotyledon. Then the growth point removal mechanism designed by the authors was used to successfully remove the growth point of rootstock seedlings. Through the force analysis of the pressing and clamping mechanism, it could be seen that the supporting force of the cotyledon to the pressing rod was getting smaller and smaller when the pressing rod rolled from middle to outside on the imitation blocks. That is, the pressing mechanism could automatically adjust the force on the cotyledon and prevent the cotyledon surface damage. At the same time, the pressing rod could extend the cotyledons to outside making the growth point fully exposed and convenient to be removed. The stock cotyledon pressing tests on 60 cucurbit seedlings were carried out by using the self-adaptive pressing and clamping mechanism and compared with that of without imitation blocks. The results showed that the success rate of the stock cotyledon pressing and clamping mechanism with the imitation blocks was 100%. It was also found that cotyledons could easily be broken by using the pressing and clamping mechanism without imitation blocks, and the breaking rate of cotyledons was 13.3%, but cotyledons was totally not broken by using the pressing and clamping with imitation blocks in the same condition. The damage rate of cotyledons surface was 21.6% by using the mechanism without imitation blocks, but it was totally not damaged by using the mechanism with imitation blocks in the same condition. The growth point of stock could easily be removed by using the mechanism with imitation blocks, and the remove rate of growth point was 98.3%, while it was only 16.7% by using the mechanism without imitation blocks. It indicated that the design of the stock cotyledon pressing and clamping mechanism with the imitation blocks was reasonable. It can better meet the requirements of the grafting and cultivation of Cucurbitaceous vegetables. The study provides a design reference for solving the problems on pressing cotyledons in the process of Cucurbitaceous vegetable grafting.