This publication is a precursor for the account of Trigonostemon (Euphorbiaceae) for the Flora of China, based on specimens at several herbaria in the U.S.A. (Harvard University, Missouri Botanical Garden, and the Smithsonian Institution) and major herbaria in China. The genus Trigonostemon (Euphorbiaceae: Crotonoideae, Trigonostemoneae) in China is revised. Twelve species and varieties are placed in synonymy, that is, Trigonostemon petelotii, T. kwangsiensis vars. kwangsiensis and viridulis, and T. lii are combined with T. bonianus; T. harmandii, T. leucanthus var. hainanensis, and T. wui are combined with T. chinensis; T. gagnepainianus and Prosartema gaudichaudii are combined with T. howii; T. heterophyllus is combined with T. flavidus; and T. lutescens is combined with T. fragilis. Trigonostemon fragilis is reported as new to Myanmar. A key to the species of Trigonostemon in China is given.