Abstract: Numerous marks of subaerial exposures indicate an important paleokarst unconformity surface on the top of the Maokou Formation in the Jianshi Badong area, Hubei, which constitutes a typical II type sequence boundary of the carbonate platform. The unconformity was formed in the terminal part of the Early Permian Maokouan aged Neoschwagerina haydeni Zone. The discovery of the unconformity is powerful evidence for denying the deep water view for the origin of the Gufeng Formation.