Passiflora menghaiensis (Passifloraceae), a new species from Menghai, Yunnan, China, is described and illustrated. The species is placed in Passiflora subgenus Decaloba, supersection Disemma, section Octandranthus. It is compared with two morphologically similar species in section Octandranthus, P. kwangtungensis and P. geminiflora. Passiflora menghaiensis differs from the preceding species by the combination of two flowers per inflorescence, the outer series of coronal filaments white, the inner series of coronal filaments light green, and puberulous fruit. A complete morphological description of P. menghaiensis is provided, together with line drawings, photographs, a conservation assessment, and a diagnostic key to fourteen species of Passiflora subgenus Decaloba supersection Disemma section Octandranthus from China.