The park and conservation area is situated in the Sankhuwasabha and Solukhumbu districts, bordered by the Arun River on the east, Sagarmatha (Mt. Everest) National Park on the west, the Nepal-Tibet border on the north and Saune Danda (ridge) to the south. The Park covers 2,330 sq. kms.

This is the only protected area in Nepal with designation of a Strict Nature Reserve. It has some of the richest and most unique pockets of plants and animals in Nepal, elsewhere lost to spreading human habitation. Stepping up the slopes are a series of vegetation zones starting with tropical sal forest below 1,000 m. elevation subtropical schima-castanopsis forest at 1,000-2000 m. fir, birch, rhododendron forests in the sub-alpine(3,000-4,000 m); and herbs, grasses and rhododendron/juniper shrubs in the alpine pas trues (4,000-5,000 m). There are 47 varieties of orchids, 67 species of bamboos, 15 oaks including Arkhoulo, 86 species of fodder trees and 48 species of primrose. Over 400 species of birds have been sighted in the Makalu-Barun area, including two species never before seen in Nepal the spotted wrenbabbler and the olive ground warbler. Wildlife includes the endangered red panda, musk deer, Himalayan black bear, clouded leopard and possibly snow leopard, in addition to more substantial populations of ghoral, thar, wild boar, barking deer, Himalayan marmot and weasel, common langur monkey and the serow. The Arun river system contains 84 varieties of fish.