Aesculus assamica is a tree and reaches stature heights of up to 32 m and a diameter at breast height of 0.6 m. The bark is light gray.The branches are gray, bald or hairy young.
The leaves are composed of 5 to 9 palmately arranged leaflets. The petiole is 8 to 30 cm long and bald to hairy. The sub-petioles are 0.3 to 1.5 cm long, glabrous to hairy, dark young glandular. The leaves are 12 to 35, rarely 7-42 cm long and 5 to 18 cm wide. Its shape is oblong-lanceolate to narrowly lanceolate. The bottom is bare, slightly hairy or young hairy on the nerves. The leaf base is truncated or rounded, the margin is cut notched up, the blade end is truant pointed up. There are 17 to 30 pair of lateral veins.