An incomplete postcranial avian skeleton is described from the Lower Cretaceous Jingchuan Formation of Otog Banner of west Inner Mongolia and referred to a new species of Cathayis, C. chabuensis sp. nov. This is the first report of a Cathayis from outside Liaoning Province. The new discovery indicates that Cathayis coexisted with Otogis genghisi, and a more detailed comparison between these two enantiithine genera shows that Otogis represents a more primitive genus than Cathayis. Our analyses further indicate that Cathayis is an arboreal bird. The discovery of a Cathayis from this region also confirms that the avian fossil-bearing Jingchuan Formation is comparable to the Jiufotang Formation of the upper Jehol Group in west Liaoning, and should be referred to the middle-late Early Cretaceous.