A new bamboo species, Yushania dezhui, from Kunming, Yunnan, China is described and illustrated in this paper. The new species used to be misidentified as Y. polytricha. Based on careful comparison of morphological features and molecular phylogeny evidence, we confirmed its identity as a new member of the genus Yushania. Yushania dezhui resembles Y. maculata, Y. polytricha and Y. weixiensis in several aspects, such as culm height and branch complement structure. However, the glabrous culm leaf sheaths and internodes, the absence of auricles and oral setae on most foliage leaves, except the one-year-old foliage leaves, the pubescence on the adaxial surface of the one-year-old foliage leaves and its limestone habitat preference can readily distinguish this new species from its related taxa. Moreover, we emphasise that individuals from various populations and molecular markers with different inheritance patterns for phylogeny reconstruction should be included in new species discovery, especially in plant groups with complex evolutionary histories.