Abstract: Acidosasa, a new genus of Bambusoideae, was discovered in South China by the authors as they engaged in the study of the taxonomy of Chinese bamboos recent years. It belongs to the tribe Arundinarieae taxonomically.This new genus is affinis to the genus Sasa Makino et Shibata but more primitive than the latter by the arboreous habit and some other characters. It is also somewhat similar to the genus Indosasa McCl. but differs from its particular spikelets.The comprehensive characters of this new genus and only one new species (Aci dosasa chinensis) known nowadays are studied morphologically in detail, with Chinese-Latin descriptions and drawings given also.The significance of the discovery of this new genus may however be valuable to the study of the resources of Chinese bamboos particularly to the research of systematic and phytogenetic purposes.