Abstract: A new ornithopod (Changchunsaurus parvus gen. et sp. nov . ) dinosaur is named and described on the basis of a specimen from the Early Cretaceous Quantou Formation at Liufangzi locality, Jilin Province, China. Ihe specimen represents the first primitive ornithopod taxon from the Cretaceous deposits in the Songliao Basin. Changchunsaurus is an interesting ornithopod in having a combination of primitive and derived characters. It shares with some ornithopod autopomorphies: paroccipital process is crescent-shaped, the jaw articulation offsets ventral to the maxillary tooth row . It shares with euomithopods the following synapomorphies: antorbital fenestra small, external mandibular fenestra absent. However, It is believed that Changchunsaurus is also more primitive than most of omithopods and marginocephalians in having five premaxillary teeth, a short edentulous anterior portion of premaxilla, a short diastema between premaxillary and maxilla teeth, the enamel on crowns of maxilla teeth and dentary teeth distribute symmetrically, and the premaxillary bill margin with that of the maxilla. Its jugal boss projects lateral face of the jugal. There is nubble structure on the lateral expansion of jugal, which is not described in other ornithopods. Changchunsaurus has a long predentary , which suggests it might have an immobile mandibular symphysis as in ceratopsians , and the predentary ventral process is longer than the lateral process. It is similar to derived omithopods in the morphology of the predentary with bilobate ventral pmcess end . Further work is needed to give precise phylogenetic relationship of the new omithopod .