To improve the grafting rate and automation of grafting robot used currently in seedling production, a high efficiency vegetable grafting robot operated by one person for cucurbitaceous seedlings cultivated in humus pots was designed based on splice grafting method. The machine consisted of six units, i.e., a scion gripping and transporting unit, a scion straight cutting unit, a stock gripping and transporting unit, a stock rolling cutting unit, a clip auto arranging and sending unit and a grafted seeding bowl auto arranging unit. Experiments were conducted in laboratory and field. Results showed that the success rate of grafting was 92% and the practical grafting rate was 285 plants per hour (with the theoretical grafting rate of 440 plants per hour). Under the same success rate of grafting, the grafting rate of this machine was 36% higher than the grafting machine for cucurbitaceous seedlings cultivated in humus pots operated by two persons.