The Assam Orang National Park on the whole is a flat land and the terrain is gentle slope from north to south. The park area enjoys typical subtropical monsoon climate. The southern and eastern boundaries of the park comprise channels, and islands of the Brahmaputra. The western boundary is an artificial boundary delimited by a foxhole from villages. The villages almost from its all sides surround the whole area. Even in the southern side, the riverine islands are now inhabited by human habitation and the national park is under continuous biotic pressure. The area consists of alluvial flood plains of the Brahmaputra.
Climate Temperature in Winter varies from 5-25ú Celsius and in summer it varies from 12-32ú Celsius
Flora The vegetation of the park is very rich. The natural forest species are like Bombax ceiba, Dalbergia sisoo, Sterculia villosa, Trewia nudiflora, Zizypphus jujuba, Litsaea polyantha, etc are found here. Among the non aquatic grassland species the prominent are Phragmites karka, Arundo donax, Imperata cylindrical, Saccarum spp. etc. The aquatic grassplants species are Andropogon spp., Ipomea reptans, Enhydra flushians, Nymphia spp., Wichornia spp. etc
Fauna Apart from the greater Indian one-horned rhinoceros, which is the dominant species of the national park, the other key species sharing the habitat, are the Royal Bengal Tiger, Asiatic elephant, hog deer, wild boar. Besides, there are other small mammals like civets, leopards, hare, and porcupines. There are more than 50 species of fish. Orang National Park in Assam is the most important habitat of the Bengal florican. The estimated population is about 30-40. Other important birds are Spot-billed Pelican (Pelicanus philippensis), Black-necked Stork (Ephippiorhynchus asiaticus), Greater Adjutant Stork (Leptoptilos dubius), Lesser Adjutant (Leptoptilos javanicus), Wooly-necked Stork (Ciconia episcopus), Rudy Shelduck (Tadorna ferruginea), Gadwall (Anas strepera), Mallard (Anas platyrhynchos), Pintail (Anas acuta), Pallas's Fishing Eagle (Haliaeetus leucoryphus) and a number of others including forest and grassland birds. Among reptiles, turtles like Lissemys punctata, Kachuga tecta, and among snakes pythons and cobras are known to frequent these in this area.