We selected 1 627 seed plants in Dehang Canyon of Hunan Province to explore the diversity composition basic rules of plant functional traits in the canyon habitat. Seven nutritional traits such as growth type, leaf type and leaf size and six reproductive traits such as sexual system, inflorescence type and fruit type were selected as the parameters for establishing the functional traits database of seed plants in this region. By statistical analysis of the database, we found that: (1) the nutritional traits of Dehang seed plants have the characteristics of both middle and south subtropical plant functional traits affected by the warm and humid environment of the canyon. The growth type was mostly perennial herbs, and the leaf was mainly mesophyllous and microphyllous, simple, papery, entire, undivided, alternate and hairless while the proportion of mesophyll was higher than that of microphyll. (2) The reproductive traits of Dehang seed plants were dominantly bisexuality, terminal and axillary infinite inflorescences, dry fruits and seeds spread by animals. There were more monoecious plants than dioecious, showing the adaptability to canyon habitat. The flowering period was concentrated from April to August, while the fruiting period was mainly from July to October. It is found that plant functional trait database plays an important role in exploring the composition rule of plant diversity in a specific environment, which is worthy of further researching and applying.