Holotype IVPP V11527 consists of a partial  skull with lower jaws, several cervical vertebrae and a partial scapula and humerus. The name of this genus was first published in Japanese in a dinosaur chart in an anonymous guidebook to a Chinese dinosaur exhibition in Japan in 1981 or 1982. The spelling Chaoyoungosaurus from that article is a transliteration provided by M. Tanimoto (pers. comm.); coincidentally, this was also its first published Latin spelling, as a nomen nudum in Zhao, 1983. The type species name, Chaoyoungosaurus liaosiensis, was subsequently published, also as a nomen nudum, by Zhao in 1985. 

Dong (1992) asserted that this dinosaur had been described and named in 1983 by Zhao & Cheng, but the citation for this reference is missing from Dong's bibliography. Dong also emended the spelling of the genus to Chaoyangosaurus. P. Sereno (pers. comm.) noted that the 1983 paper by Zhao & Cheng with the spelling Chaoyangosaurus was almost certainly not properly published and that spelling is also a nomen nudum.

Regardless of these earlier spellings, the generic name finally became Chaoyangsaurus, with type species named Chaoyangsaurus youngi, when the dinosaur was formally described by Zhao, Cheng & Xu in the December 13, 1999 issue of the Journal of Vertebrate Paleontology. This is the spelling previously used by Sereno in his June 25, 1999 article in Science on dinosaur phylogeny.

The new ceratopsian specimen, Chaoyangsaurus youngi gen. et sp. nov., was collected from the Tuchengzi Formation (Middle or Late Jurassic) of Liaoning, China. Distinctive characteristics of the new species include quadratojugal overlapping posterior side of quadrate shaft; lack of a broad lateral surface of the quadrate shaft; convex posterior margin of the ventral portion of the quadrate; a ridge between the planar lateral and Ventral surface of the angular. The discovery of Chaoyangsaurus youngi extends the record of ceratopsian from back in time from the Early Cretaceous into the Middle or Late Jurassic. Some characters of C. youngi may suggest a close relationship between Ceratopsia and Heterodontosauridae.