The invention discloses a tunnel automobile lane changing detection method based on supersonic wave detection. According to the method, supersonic wave information generated when a vehicle changes a lane and steps on a driving line is detected through an ultrasonic sensor, and a controller processes the supersonic wave information and then emits information controlling shooting of a camera, such that a shooting system is not started unless the vehicle changes the lane, and when the vehicle does not change the lane or step on the line, the camera is at a dormancy state, thus energy and storage information of a server are effectively reduced, and the work efficiency is improved.