The tiltrotor aircraft has attracted widespread attention in the aviation industry because of its advantages from both the helicopter and fixed wing aircraft, such as vertical takeoff and landing, high flight speed, and long range. However, the special structural design of the tiltrotor aircraft makes it having some special dynamic instability problems, among which the whirl flutter is an instability problem that couldn’t be ignored in the tiltrotor aircraft design. From the beginning of the research of the tiltrotor aircraft, the whirl flutter problem has been the main factor restricting the development of the tiltrotor aircraft. For this reason, researchers have carried out a lot of analytical and experimental studies to understand the mechanism and influencing factors of the whirl flutter during the development of the tiltrotor aircraft. The mechanism of the whirl flutter, and the research on whirl flutter during the development of the tiltrotor aircraft such as XV-3 and XV-15 are reviewed. The purpose is to provide technical reserve for the design of the tiltrotor aircraft in China in the future.