The Early Cretaceous pterosaurs are abundant in western Liaoning Province, China with two pterosaur assemblages. The upper one, pterosaur assemblage of the Jiufotang Formation is featured by some advanced pterodactyloid clades including toothless Tapejaridae and Chaoyangopteridae, which shows difference from the lower one, pterosaur assemblage of the Yixian Formation. A new large-sized pterosaur skeleton is described here, which was found from the Jiufotang Formation of Jianchang Basin, western Liaoning. This specimen can be assigned to the genus Shenzhoupterus within the family Chaoyangopteridae by having following features: toothless jaws, rostral index being 3.7, long and slender premaxillary bar dorsally bounding the nasoantorbital fenestra, caudal extremity of the very large nasoantorbital fenestra posterior to the jaw joint, and broader base of premaxillary process of jugal. It is also distinguished from Shenzhoupterus chaoyangensis in having the characters such as: large size with the wing-span about 2.05 meters, straight occlusal margin of upper and lower jaws, longer postorbital process with slightly wider base than lacrimal process of jugal, and sequentially decreased fourth to seventh cervical vertebrae. Thus a new species, Shenzhoupterus sanyainus sp. nov., is erected. This new taxon possesses the largest wing-span among the Early Cretaceous toothless pterosaurs from western Liaoning Province. The finding also enriches the elements of pterosaur assemblage of the Jiufotang Formation, and is of significance for understanding the anatomy and ecological habits of chaoyangopterids.