A tree to about 65 ft high; shoots of the year glossy, dark reddish brown, orange-brown the second year, faintly grooved, glabrous except for some down in the grooves; buds ovoid-conic, resinous but not strongly so. Leaves rich green, leathery and firm, those on the lower non-coning branches ascending and parted above, up to 2 in. long, with pale green stomatal bands beneath, the margins slightly revolute. Cones ovoid-cylindric, 23⁄8 to 31⁄2 in. long, violet when young, brown when mature; bract-scales included, or the cusps slightly exserted.
This fir, described by Keith Rushforth in 1984, is intermediate between A. forrestii and A. chensiensis subsp. salouenensis, but nearer to the former, differing most obviously in the longer leaves with pale stomatal bands. Some at least of the cultivated trees were raised from seeds received under Forrest's 30663, but do not agree with the herbarium specimen under that number, which is A. chensiensis. There is no herbarium specimen so far collected in the wild that matches A. chengii, and the type chosen by Rushforth is from a tree at Westonbirt, Gloucestershire, grown as A. fargesii. There are two trees in the Hillier Arboretum, Hampshire, also originally under that name (K. Rushforth, Notes Roy. Bot. Gard. Edin., Vol. 41, pp. 333-8 (1984)). The larger of these measures 51 × 5 ft (1986).