Abstract: A new genus and species of a basal ornithurine bird is reported from the Lower Cretaceous Jiufotang Formation of Jianchang, Liaoning, China. It is represented by a nearly complete articulated skeleton of a sub-adult individual. It is distinguishable from other known ornithurines by possessing a combination of features including at least 16 small and conical teeth on the dentary, scapula strongly curved, metacarpal I robust and wider than other metacarpals, first manual digit long and extending beyond distal metacarpal II, and length ratio of humerus+ulna+metacarpal II to femur+tibiotarsus+tarsometatarsus is approximately 1.1. Phylogenetic analysis indicates that the the new taxon is a basal ornithurine.Jianchangornis represents the second Early Cretaceous bird with the preservation of a predentary bone, which may further confirm that a predentary could be a feature common to Mesozoic ornithurines. The advanced features of the pectoral girdle, sternum and wings of the new bird indicate its powerful flight capability, and the hindlimb bone and toe proportions as well as the ungual morphology suggest a terrestrial locomotion similar to those of Yanornis and Yixianornis. The associated fish fragments may indicate a piscivorous diet consistent with the dentation of the new bird. The discovery of a new basal ornithurine further shows that the diversification of the Ornithurae is probably no less than the enantiornithes, and the near lakeshore adaptation had definitely played a key role in the early ornithurine radiation.