With the gradual progress of urbanization in china, more and more children who used to live in rural areas enter the city with their parents, resulting in the increasing number of children living in the city year by year. this group generally has little contact with nature and lack of opportunities for labor experience. In view of this, the paper aims to a vegetable planting device suitable for the use of ordinary families in the city, which conforms to the cognitive characteristics of children and can arouse their interest in participation, is designed to help urban children to actively recognize vegetables and cultivate their love for land and labor. Based on design psychology, the characteristics of children's cognition (including declarative knowledge and procedural knowledge) and motivation (including primitive motivation and social motivation) were analyzed, and the vegetable planting devices for children were designed from morphological and functional structure respectively. The design of children vegetable planting device based on cognitive motivation analysis takes into account the motivation of children to use the device, as well as the experience of knowledge acquisition, fun and labor in the process of using the device, so that the design object can achieve the goal of being useful, easy to use and user-friendly.