Here we describe new arthrodires (stem-Gnathostomata, Placodermi), Cuanyu liui gen. et sp. nov., and Cuanyu sp., from the Lochkovian (Xitun Formation, Lower Devonian) of Qujing, Yunnan, southwestern China. The new genus resembles other actinolepid arthrodires in the general arrangement of the skull roof plates, the ornamentation, and the sensory line pattern. Furthermore, it displays a single fused preorbital plate, a diagnostic feature of the family Actinolepidae. Cuanyu differs from other members of the Actinolepidae in possessing a deeply embayed posterior margin of the skull roof. The phylogenetic analysis supports its position within a monophyletic Actinolepidae, as the sister group of Szelepis. As one of the earliest arthrodires, Cuanyu is informative in revealing the character transformation in the early evolution of this diverse group of jawed vertebrates.