[1] The name Huaxiagnathus is derived from the Chinese Hua Xia, 華夏, a traditional word for "China", and from the Greek gnathos, Latinised into gnathus, meaning "jaw."

The holotype (CAGS-IG-02-301, Chinese Academy of Geological Sciences, Beijing) specimen was collected from the Yixian Formation (Jehol Group, Aptian) at Dabangou Village, Sihetun area, near Beipiao City, in western Liaoning Province.

[1] Another, larger specimen of Huaxiagnathus was discovered earlier in the Yixian Formation of the Sihetun area (NGMC 98-5-003, National Geological Museum of China, Beijing), but damage and mistakes made during its preparation rendered it unsuitable as a holotype.

[1] In 2024, Andrea Cau published a study on the phylogenetics of compsognathids and immature theropods in general that called the assessment of Huaxiagnathus within Compsognathidae into question.

Siamraptor Siamotyrannus Streptospondylus Xuanhanosaurus Poekilopleuron Piveteausaurus Piatnitzkysaurus Marshosaurus Leshansaurus Eustreptospondylus Condorraptor Asfaltovenator Sciurumimus Nedcolbertia Magnosaurus Duriavenator Afrovenator Compsognathus longipes Compsognathus corallestris Torvosaurus tanneri Torvosaurus gurneyi Megalosaurus Scipionyx Wiehenvenator Iberospinus Baryonychinae Spinosaurinae Allosauroidea (Incl.