Abstract: The Kunyang Group in the Central Yunnan Province, whose stratigraphic sequence and stratigraphic correlation are controversial, are always the research focus of Precambrian geology. Two zircon dating ages (878.5±4.7Ma and 878.0±4.0Ma) of tuff bedding from the Lubiao Formation in Yimen County are reported in this paper. Zircon dating of tuff bedding indicates that the formation occurred in Middle Neoproterozoic, which is the first report from the Lubiao Formation. Combined with a large number of high precision ages obtained from Kunyang Group, these stratigraphic ages provide important evidence for the acceptable division of Kunyang Group, and also offer reliable chronological data for the setting up of the Qingbaikou System in Southwest China.