The head is darker than the rest of the body, especially in males, and contrasts with pure white markings on the lips, around the nose, and the throat just below the chin.

[3] Adult male Thorold's deer have antlers, measuring up to 110 cm (43 in) in beam length, and weighing up to 4 kg (8.8 lb).

Other distinctive features include longer ears than most other deer, lined with white hair, and large metatarsal and preorbital glands.

Their nasal cavities are unusually large, allowing them to breathe in rarified high altitude air, while the thick hair protects against the cold.

The red blood cells in this species are smaller than average for similarly sized mammals, and are very numerous, both features that increase its ability to take up limited amounts of oxygen.

[3][8] However, they are found only in scattered populations across these regions, apparently being most numerous in eastern Sichuan Province, where they are known from Garzê Tibetan Autonomous Prefecture (to the west of Ya'an and Chengdu).

[9] Further to the west, in Qinghai, the species is commonly known from the areas around Yushu City and Nangqên, Zhidoi and Zadoi Counties,[10] while the northern extent of their range appears to be the mountains between Jiuquan and Haixi Mongol and Tibetan Autonomous Prefecture.

Their ideal habitat is often located well-above the treeline,[3] and they are known for frequenting elevations between 3,500 to 5,100 metres (11,500 to 16,700 ft)—among the highest of any deer species in the world, besides the South American taruca (Hippocamelus antisensis).

The white-lipped deer also migrates between elevations, seasonally; as the weather cools in the autumn, they descend from their high-elevation spring-summer pastures, where the conditions are more comfortable (and the swarms of biting insects are less prolific), down to lower, wind-sheltered woodlands and valleys where they will stay for the duration of winter.

They have few natural predators, although Himalayan wolves and snow leopards have been known to eat Thorold's deer on occasion,[3][13] and stray or feral dogs may target fawns.

Males compete with one another in a manner similar to other deer - wrestling with antlers, scent marking, visual displays, and grunting warning sounds.

[3] Thorold's deer is found only in scattered populations across its former range, although the remoteness of its preferred habitat makes it difficult to study in detail.