Yuanmousaurusjiangyiensis gen. et sp. nov. is erected based on an incomplete skeleton. It is characterized by more complex structures of the neural arches in the dorsal vertebrae than those in Omeisaurus, but less complex than those of Euhelopus; the dorsal vertebra bears 9 laminae, forming three cavities on the lateral surface of the neural arch; the dorsal vertebral neural spines with dorsoventrally-oriented cavities are similar to those of Omeisaurus and Patagosaurus. Yuanmousaurus is more primitive than Euhelopus, but more derived than Omeisaurus. The similar dorsal vertebral structure between Yuanmousaurus and Patagosaurus may indicate that they have a close relationship to each other.