Huanansaurus is an extinct genus of oviraptorid dinosaur that lived approximately 72 million years ago, between the Campanian and Maastrichtian, during the latter part of the Cretaceous period in what is now China, in the Nanxiong Formation.
Many unique traits of Huanansaurus have been established. Several of these are autapomorphies. Of the quadrate bone the lower condyles are positioned behind the upper head. The transverse nuchal crest on the rear skull roof is not very prominent. In the lower jaw the angular bone forms a major part of the lower rim of the outer side opening. The front point of the lower jaw is obliquely protruding to above under an angle of less than 45° with the symphysis, the fused point of the lower jaws. The shelf formed by the symphysis is moderately large, equal to about a fifth to a fourth of the total jaw length. The dentary bone is pneumatised. The lower rear branch of the dentary is twisted, causing its outer side to be somewhat directed to below. The first metacarpal is long and slender with its transverse width equal to a fifth of its length. The hand claws have prominent lips on their upper rears.
In addition, an unique combination of in themselves not unique traits is present. The temporal opening on the skull roof is round and much smaller than the temporal opening of the skull side. The rear branch of the praemaxilla touches the lacrimal bone and features a prominent opening at this point, on the rear underside. The upper rear branch of the dentary covers the outer side opening of the lower jaw and has a concave lower rim.
Huanansaurus was, within the Oviraptoridae, placed in the Oviraptorinae, as a sister species of Citipati.