Abstract: The oviraptorosaurian theropod Caenagnathasia was first described from the Late Cretaceous (Turonian) vertebrate assemblage from the Bissekty Formation of the Kyzylkum Desert, Uzbekistan. Here we report a partial pair of oviraptorosaurian fused lower jaws, comprising the symphysial region, from the Upper Cretaceous (Campanian) Iren Dabasu Formation of Nei Mongol, China. This mandibular fragment can be referred to Caenagnathasia based on the following shared characters: dentaries fully fused, symphysial portion of dentary not downturned, anterior part of dorsal margin of dentary broadly concave in lateral view, lingual ridge present at margin of occlusal surface on each dentary, lingual ridge bears apical projection, vascular grooves and associated foramina do not extend to dorsal surface of symphysis, and anterior occlusal groove present. This new specimen extends the temporal and geographic range of Caenagnathasia to the Campanian of China.