The flying wing of the beetle exhibits unique wing spreading–flying–collecting behavior in the process of flight, which is the best bionic object for flapping wing aircraft design. In this paper, through the motion behavior observation system, the behavior analysis of beetle spreading–flying–unfolding wings is carried out, the kinematic parameters of the whole flight process are obtained, and the flow field visualization of the above behavior is studied using the smoke line method. During the flapping process, the flying wing of the beetle is spread out one by one in two stages, and the wingtip trajectory is in the shape of "W" when the wing is folded. The unique microhair structure on the sheath wing can provide sufficient friction to facilitate the folding of the flying wing. When flying, the wingtip trajectory of the beetle is in the shape of "8", and the flying wing is deformed in the process of downstroke and supination, which provides additional unsteady lift for the beetle flight. The enhanced leading edge vortex and surrounding leading edge vortex produced during the upstroke and downroke further reveal the unique high-lift mechanism of beetle flight. Based on the above research on the flight mechanism of the beetle, a flapping-wing aircraft imitating the beetle is designed.