Its remains have been found in the Jiufotang Formation at Chaoyang (People's Republic of China) dated to the early Aptian age, around 120 million years ago.

All three had teeth, though in Yixianornis the tips of the jaws were toothless and pockmarked with small pits and grooves, possibly indicating the presence of a beak.

[3] The breastbone bore a strong keel for the attachment of flight muscles, and contained a distinct opening or fenestra, a unique characteristic of yanornithiformes.

The wishbone (furcula) of Yixianornis was more narrow than in its relatives, and its shoulder blade was much shorter, only half the length of the upper arm bone (humerus).

[3] The feathers of Yixianornis are unique among those preserved in other Mesozoic bird specimens, and have allowed scientists to infer its probable lifestyle.

The rectrical bulb and plough-shaped pygostyle allowing for tail fanning is also a unique characteristic of ornithurine birds, of which Yixianornis is among the earliest known.

[3] In a 2006 study, Julia Clarke, Zhou Zhonghe and Zhang Fucheng found that the ability to fan the tail, along with the broad wings, show that it probably preferred environments with dense vegetation, where high maneuverability in flight would be necessary.

Clarke et al. found that Yixianornis was the most primitive bird to display an essentially modern pygostyle and fan of tail feathers.