Abstract: This paper summarizes the recent discoveries of Mesozoic birds from Late Jurassic to Early Cretaceous in Liaoning, China. Most of these fossils can be refered to the avian subclass: Sauriurae, only Chaoyangia to Ornithurae. The earliest diversification and big development of birds from Late Jurassic to Early Cretaceous as well as the peculiar geological background and depositional environment in Western Liaoning constitute the main reasons for the appearance of abundant Mesozoic bird fossils in this area. In this region, the continental Jurassic- Cretaceous boundary being put between the Confuciusornis bearing Yixian Formation and the Cathayornis and Chaoyangia bearing Jiufotang Formation is proposed.