Langtang National Park represents some of the best examples of graded climatic conditions in the central Himalaya. Elevational gradients (ranging from mid-hills to alpine) coupled with complex topography and geology have produced a rich biodiversity.

Biodiversity of the Langtang National Park is varied. The forest type Most striking feature of the park is the variety of vegetation types. Eight vegetation types belonging to tropical, subtropical, temperate, sub alpine and alpine zone exist. The important forest types are: 

1. Tropical Zone (below 1,000m),
2. Subtropical Zone (1,000 – 2,000m),
3. Temperate Zone  (2,000 – 3,000m),
4.  Sub alpine zone (3,000 – 4,000m ), 
5.  Alpine zone (4,000 – 4500m)

Sub-tropical vegetation characterized by Sal (Shorea robusta) forest in the southern section of the park is gradually taken over by hill forest (2000-2600m) consisting of Chirpine, Rhododendron, and Nepalese alder. The temperate zone (2600-3000m) is covered mainly by oak forest fading to old growth forest of silver fir, hemlock, and larch in the lower sub-alpine zone (3000-3600m). The Nepalese larch (Larix nepalensis), the only deciduous conifer in the region, is found in this park and few places elsewhere. Throughout these zones different species of Rhododendron such as R. arboretum, R. barbatum, R. campanulatum, and R. lepidotum (scrubs) to name a few, form a colorful under story. Tree species such as birch, silver fir, Sorbus microphyla and twisted Rhododendron campanulatum are found near the tree line. It is here at 4000m Juniper and Rhododendron shrubs (R. anthopogon) slowly dissolve into expansive alpine grassland meadows.

Langtang's expansive high meadows provide summer habitat for numerous ungulate species such as musk deer and Himalayan tahr. The park is also well known for its populations of red panda, Himalayan black bear, snow leopard, wild dog, ghoral, serow and more than 250 species of birds.