A new bittersweet species, Celastrus obovatifolius X. Y. Mu & Z. X. Zhang (Celastraceae) is described from China. It is morphologically most similar to C. orbiculatus Thunb., but differs in having lamellate pith, obovate leaves, flower stalk with an articulation in its upper half, and terminal and axillary inflorescences. This is the first study using scanning electron microscope (SEM) to study the seed micromorphology of Celastrus L., which can provide valuable characters for species identification in the genus.