Hongshanornis is a genus of ornithuromorph birds known from early Cretaceous lake deposits of the Yixian Formation, Inner Mongolia, China.

It is closely related to Longicrusavis, which existed alongside Hongshanornis in the Dawangzhangzi ecosystem, and is very similar to the later Parahongshanornis from the Jiufotang Formation.

[2] Hongshanornis longicresta was a small species, especially compared to other early ornithuromorphs (birds with a modern tail anatomy), about the size of a thrush, and adult specimens are estimated to have weighed about 50 grams (1.8 oz) in life, with a wingspan of about 320 millimetres (1.05 ft).

[2] The skull in all known specimens is poorly preserved, but in general appears to have had a narrow snout compared to the closely related Longicrusavis.

[2] In their 2024 description of the enantiornithine Neobohaiornis, Shen et al. noted a superficially crest-like arrangement of feathers at the top of the bird's head.

They proposed that this (and similar arrangements in other compressed fossil birds like Hongshanornis) was the result of post-mortem taphonomic distortion.

The overall shape of the tail was rounded and wedge-shaped when viewed from above; due to the symmetrical feathers, the sides of the tail were probably not held fully fanned into the wind but swept back, forming a partially fanned wedge, as in some modern birds like accipiters, tyrant flycatchers and sunbitterns.

Though still considered probably wading birds, they probably had a more generalized diet than previously assumed, with the different snout shapes present in different members of the group indicating niche portioning within a general wading ecology (Hongshanornis lived alongside the closely related Longicrusavis, and both were very similar to each other except for the shape of the snout).

Given the overall wing shape and comparison to modern birds, Hongshanornis probably flapped continuously when flying at lower speeds, and switched to bounding flight (rapid flapping alternating with periods of ballistic forward motion with the wings partly folded) at higher speeds.