Aristolochia wenshanensis Lei Cai, D.M.He & Z.L.Dao, a new species of Aristolochiaceae from southeastern Yunnan, China, is described and illustrated. The new species is morphologically most similar to A. mulunensis Y.S.Huang & Yan Liu in the shape of the leaf blade and perianth, but it can be easily distinguished by structure and color of the flower, shape of leaf blade base, especially the perianth shape, colour and texture. According to morphology the new species belongs to Aristolochia subgenus Siphisia. We also provide a table and notes to distinguish several other morphologically similar Aristolochia species.