Based on the multiple field surveys in 2017 and 2018, the study combined the relevant data to analyze the seed plants in Sanjiangyuan National Park and analyze the composition, nature and characteristics of the flora. The results showed that: (1) there are 832 species of 232 genera and 50 species of seed plants in Sanjiangyuan National Park. Droughttolerant and coldtolerant perennial herbs are the main components, and woody plants are less. It is the core distribution area of seed plants in Sanjiangyuan Nature Reserve. (2) The park has the highest plant resource richness in the Yangtze River source park, and the Lancang river source park and the Yellow River Source Park are successively decreasing. Among them, 244 seed plants are distributed in all three parks. (3) At the level of the family, the small and mediumsized departments constitute the main body of the park, while the 12 larger and large families represented by the grass family together constitute the superiority of the seed plants in the park. At the genera level, a single genera constitutes the main body of the Sanjiangyuan National Park genera, and the medium genera contains the largest number of seed plants. (4) The type of distribution area of this district is mainly distributed in the world. Except for cosmopolitan, the section of the park mainly reflects the distribution characteristics of temperate nature. (5) The type of distribution area of genera has obvious temperate nature, closely related to Eurasia, and the distribution of north temperate is the main component. (6) The species of seed plants in this area are divided into two categories: endemic to China and endemic to nonChinese species. The distribution of endemic species in China is closely related to the Hengduan Mountains, which affects the formation of the flora. The distribution of nonChinese endemic species has obvious temperate nature under the joint influence with central Asia and East Asia and secondary influence with temperate Asia and North temperate. (7) The richness of seed plant resources, the diversity of life forms and the distribution characteristics of temperate nature of families, genera and species in this park fully reflect that the plant flora of the park is compatible with its unique geographical location and climatic conditions.