Political Geography: The park area falls in five districts: Kokrajhar, Chirang, Baksa, Udalguri, and Darrang in the state of Assam in India.

The park is divided into three ranges. The western range is based at Panbari, the central at Bansbari near Barpeta Road, and the eastern at Bhuiyapara near Pathsala. The ranges are not well connected; while two major rivers need to be forded in going from the centre to the Panbari, there is a rough trail (the daimAri road) connecting the central to the eastern range. Most visitors come to Bansbari and then spend some time inside the forest at Mathanguri on the Manas River at the Bhutan border.

Physical Geography: Manas is located in the Eastern Himalaya foothills. The park is densely forested. The Manas River is the main river, a major tributary of Brahmaputra River. The Manas River flows through the west of the park, further it splits into two separate rivers, the Beki and Bholkaduba. Manas and five other small rivers flow through the National Park which lies on a wide low-lying alluvial terrace below the foothills of the outer Himalaya. The river also acts an international border dividing India and Bhutan. The bedrock of the savanna area in the north of the park is made up of Limestone and sandstone, whereas the grasslands in the south of the park are made up of deep deposits of fine alluvium. The combination of Sub-Himalayan Bhabar. Terai formation along with riverine succession continuing up to Sub-Himalayan mountain forest making it one of the richest biodiversity areas in the world. The park is 950 km². in area and situated at a height of 61m to 110m above mean sea level.

The minimum temperature is around 15 degree C. and maximum temperature is around 37 degree C.

Heavy rainfall occurs between May and September and the annual average rainfall is around 333 cm.

Vegetation: The Burma Monsoon Forests of Manas lie on the borders between the Indo-Gangetic and Indo-Malayan biogeographical realms and is part of the Brahmaputra Valley Biogeographic Province. The combination of Sub-Himalayan Bhabar Terai formation with riverine succession leading up to Sub-Himalayan mountain forest makes it one of the richest biodiversity areas in the world.

The main vegetation types are:
* Sub-Himalayan Light Alluvial Semi-Evergreen forests in the northern parts.
* East Himalayan mixed Moist and Dry Deciduous forests (the most common type).
* Low Alluvial Savanna Woodland, and
* Assam Valley Semi-Evergreen Alluvial Grasslands which cover almost 50% of the Park.
       
Much of the riverine dry deciduous forest is at an early successional stage. It is replaced by moist deciduous forest away from water courses, which is succeeded by semi-evergreen climax forest in the northern part of the park. A total of 543 plants species have been recorded from the core zone. Of these, 374 species are dicotyledons (including 89 trees), 139 species monocotyledons and 30 are Pteridophytes and Gymnosperms.

 The Park's common trees include Aphanamixis polvstachya, Anthocephalus Chinensis, Syzygium cumini, S.Formosumm,  Bauhinia purpurea, Mallotus philippensis, Cinnamomum tamala, Actinodaphne obvata Bombax ceiba, Sterculia villosa,  Dillenia indica, D. pentagyna,  Careya arborea, Lagerstroemia parviflora, L.speciosa, Terminalia bellirica, T. chebula, Trewia polycarpa, Gmelina arborea,Oroxylum indicum and Bridelia spp. The Grasslands are dominated by Imperata cylindrica,  Saccharum naranga,  Phragmites karka, Arundo donax, Dillenia pentagyna, Phyllanthus emblica, Bombax ceiba, and species of Clerodendrum, Leea, Grewia, Premna and Mussaenda

The sanctuary has recorded 55 species of mammals, 380 species of birds, 50 of reptiles, and 3 species of amphibians. Out of these wildlife, 21 mammals are India’s Schedule I mammals and 31 of them are threatened.

The fauna of the sanctuary include Asian Elephants, Indian Rhinoceros, Gaurs, Asian Water Buffaloes, Barasingha, Indian Tigers, Leopards, Clouded Leopards, cat, Capped, Golden Langurs, Assamese Macaques, Slow Loris, Gibbons, Smooth, Sloth Bears, Barking Deer, Hog Deer, Black Panther, Sambar Deerand Chital.

The park is well known for its rare and endangered wildlife which is not found anywhere else in the world like the Assam Roofed Turtle, Hispid Hare, Golden Langur and Pygmy Hog.

Manas houses more than 450 species of birds. Manas have the largest population of endangered Bengal Florican. The major other birds includes Giant Hornbills, Jungle Fowls, Bulbuls, Brahminy Ducks, Kalij Pheasants, Egrets, Pelicans, Fishing Eagles, Serpent Eagles, Falcons, Scarlet Minivets, Bee-Eaters, Magpie Robins, Pied Hornbills, Grey Hornbills, Mergansers, Harriers, Ospreys and Herons.