The Himalaya is regarded as one of the most important biodiversity hotspots on earth. Based on the combination of species lists and distribution data on the southern and northern slopes of the Himalaya collected by previous studies, as well as supplement of online databases, this study summarized the distribution of Himalayan seed plants in China, India, Nepal and Bhutan, and analyzed the characteristics, species composition similarity, floristic composition and elevational distribution patterns, which would provide data support for Himalayan biodiversity studies and conservation. The results show that: (1) the Himalaya harbors 11 875 seed plants species (belonging to 2 086 genera and 223 families), of which 7 906 are herbaceous species (66.6%), 2 583 are shrub species (21.8%) and 1 386 are tree species (11.7%), respectively. (2) Families with a large number of species (including Asteraceae, Orchidaceae, Poaceae, Fabaceae, Ericaceae and other families) contain 7 456 species, accounting for 62.8% of the species in the Himalaya, and genera with a large number of species (including Rhododendron, Primula, Pedicularis, Saxifraga, Carex and other genera) contain 2 235 species, accounting for 18.8% of the Himalayan plants. (3) Floristic components of family and genus are mainly tropical element (accounting for 51.6% and 54.2%, respectively). (4) China, India, Nepal, Bhutan of the Himalaya have 8 571, 5 306, 5 304 and 5 613 plant species, respectively, and species similarity between Nepal and Bhutan is the highest (The similarity of family, genus and species are 92.7%, 75.0% and 54.9%, respectively), while China and India have the lowest species similarity (The similarity of family, genus and species are 83.7%, 61.9% and 31.1%, respectively). (5) With an increase of elevation, species richness first increased, then fluctuated horizontally, and finally decreased rapidly, and most species occurred at low-intermediate elevations (1 500-3 500 m), only a few herbaceous plants are found at elevation above 4 000 m.