Manglietia crassifolia Q. N. Vu, N. H. Xia & Sima, a new species of Magnoliaceae from Lao Cai Province in northern Vietnam, is described and illustrated. It is most closely related to M. dandyi (Gagnep.) Dandy and M. megaphylla Hu & W. C. Cheng, but differs in its broadly ovoid terminal buds, the thickly leathery leaf blade that is abaxially densely villous with appressed, ferruginous-brown, matted hairs, the purplish cream outermost tepals, the glabrous and purplish red stamens with obtuse appendages, and the ellipsoid, very short-beaked fruits.