The invention discloses a bridge detection robot based on a four-axle aircraft, comprising the four-axle aircraft. The main machine body of the four-axle aircraft is axially provided with a trough installation channel; the installation channel is internally provided with a self-adaptation matching regulation device; the main machine body is also provided with an onboard flight control unit and an installation platform, wherein the installation platform is connected with the main machine body through the self-adaptation matching regulation device and is provided with a shooting unit; a master control system consists of the onboard flight control unit and a ground control unit; and an image data processing system consists of the shooting unit and a ground image processing unit. The invention realizes the automatic sensing and line walking of a bridge detection position through a wireless shooting controller and high-accuracy distancer by utilizing the four-axle aircraft with superhigh stability in the sky as a basic equipment carrier and can also move high-accuracy photographing equipment to a bridge position to be detected, thereby realizing the automatic bridge damage detection and identification under no-man control.