Abstract: The skeletons and surrounded plumages aura fossil of Confuciusornis sanctus discovered in early Cretaceous lacustrine sedimentary stata in western Liaoning Province, China shed new light on the early evolution of their avian flight as follows: ① Confuciusornis sanctus’ sternums were weak and less keeled, a signal its poor flight aptitude, while a modern skillful flying bird’s sternum is strong and carinate with bulky pectoral flight muscles accounting for more than 20 percent of the body weight. ② Confuciusornis sanctus’ forelimbs possess three flexible digits with large and sickle-like claws apt for tree climbing yet decreased flying function. In contrast to the corresponding positions of the modern sophisticated flying birds, it possessed an alula for regulating the flow of air passing the surfaces of the wings to ensure smoothly and avoid the stall at a large angle of incidence during taking off or landing. On the other hand, Confuciusornis sanctus exhibited some advanced features: ① Confuciusornis sanctus’ portable toothless horny beaks suited to pecking; a shorten tail of only 8 caudal vertebrae and a pygostyle for attachment of the fan-like tail feathers, providing critical surfaces, beneficial to controlling flight direction and speed instantly, especially during taking off and landing; an inflated evidently proximal part of the humerus which had an oval depression, perhaps showing an air sac system, lightened the structural weight of the skeleton. ② Confuciusornis sanctus had developed feather system, almost same to the modern flying birds and beneficial to flight. The wing-shape of a Confuciusornis sanctus was short and broad as that in a chicken-like bird, indicating possible similar flight manner.