Castanopsis paucispina is a tree in the family Fagaceae. The specific epithet paucispina means 'few spines', referring to the sparsely spined cupule.
Castanopsis paucispina grows as a tree up to tall with a trunk diameter of up to . The brown bark is smooth to slightly cracked. The coriaceous leaves measure up to long. Its to roundish nuts measure up to long.
Castanopsis paucispina is endemic to Borneo. Its habitat is hill dipterocarp forests up to elevation.