With the development of specialization and large-scale vegetable planting in China, factory seeding was widely used, and there was high requirement for sowing. Vegetable tray seeding machinery is one of the core equipment of vegetable seedling. In order to solve the problems of low productivity, high labor intensity in manual seeding and the current planting machine being not suitable for the need of small and medium sized planting greenhouses in China, the automatic seeding device used in greenhouses was designed on the base of the analysis of characteristic parameters of rape and cucumber seeds. One side of the seeding device can be folded in order to carry it easily. The size of folded seeding machine was 500mm×500mm×750mm.The device was designed with a multifunctional integrated structure, including hole-punching and seeding, which simplified the working procedure. Both the hole-punching and seeding can be achieved accurately through detecting the position of the notch in the tray by laser sensor. The success rate of seed adsorption was an important factor of seeding machine. The success rate of adsorption would directly affect the success rate and production efficiency of seeding machine. Experimental results showed that the size of suction head had effect on suction success rate when pressure was decided. The suction success rate was high when the diameter of suction head was within 0.6~1.2mm and the vacuum degree was 8kPa. Selecting the diameter of 0.6mm，the success rate reached over 90% when pressure was higher than 6.2kPa for rape seeds and 8.3kPa for cucumber seeds. By orthogonal experiment, it was found that the best adsorption effect was with vacuum degree of 10kPa and diameter of 0.6mm. Compared with manual seeding, the efficiency of seeding machine was improved by 12.9 times. The research provided a new structure and design idea to solve problem in seeding.