Hemilophia cardiocarpa (Brassicaceae), the sixth species of the Chinese endemic genus Hemilophia, is described and illustrated. This plant is found in the Jiaozishan Mountains in Dongchuan District, northern Yunnan, southwest China. Morphologically, it shows close relationships with H. rockii and H. pulchella, but differs from it in the leaf shape and size, inflorescence, flower size, shape of fruit and length of its pedicel. An updated key to the taxa of Hemilophia is provided.