The majority of vegetation in the Park is dominated by blue pine and different species of rhododendrons. The other major species includes Himalayan spruce (Picea smithiana), Oak (Quercus semicarpifolia), Himalayan cypress (Cupressus torulosa), Birch (Betula utilis), Deodar (Cedrus deodara), Lauth salla (Taxus wallichiana), walnut (Juglans regia) and Himalayan poplar (Popolus ciliata). Rangelands are dominated by herbs and grass species like Carex atrofusca, Juncus himalensis, Kobresia duthei, Parnsia nubicola, Polygonum spp. Juniperus indica, J.lindleyana and Aletris pauciflora.
Major Non–Timber Forest Products(NTFPs) and medicinal plants includes; Kutki (Neopicrorhiza scrophulariflora), Panchaunle (Dactylorhiza hatagirea), Jatamansi (Nardostachys grandiflora), Satuwa (Paris polyphylla), Sugandhwal (Valeliana jatamansi), Attis (Aconitum heterophyllum), Padmchal (Rheum emodii) and Guchi Chayau (Morchella conica).
Out of 210 mammal species recorded in Nepal, 52 species have been recorded in the park. The Park is home for Musk Deer (Moschus chrysogaster),Himalayan Black Bear (Ursus thibetanus), Red Panda (Ailurus fulgens), Leopard Cat (Prionailurus bengalensis) Himalayan Ghoral (Nemorhaedus goral),Himalayan Thar (Hemitragus jemlahicus), Wild Dog (Cuon alpines) and Wild Boar (Sus scrofa).
Three endemic species of Snow Trout viz. Schizothorax macropthalus, Schizothorax nepalensis and Schizothorax rarensis have been recorded in the lake (BPP, 1995). Schizothorax rarensis is endemic to this lake.
Out of 778 birds recorded in Nepal, 272 species have been recorded in the park. Rara lake serves as an important transit point for migratory waterfowls across the Himalayas. Common Coots (Fulica atra) are plentiful in the lake and several of them stay even for the whole year. Tufted Duck (Aythya fuligula), Mallard (Anas platyrhynchos), Great-created grebe (Podiceps nigricollis), Red-crested pochard (Netta ragina), and Gulls (Larus spp.) visit the park during winter. Other common birds of the park are Cheer Pheasant (Catreus wallichii), Snow cock (Teragallus himalayensis), Chukor partridge (Alectoris chukor), Impeyan Pheasant (Lophophorus impejanus), Kalij pheasant (Lophura leucomelana)and Blood pheasant (Ithaginis cruentus).