The invention discloses a system and method for detecting settlement of a road foundation. The system comprises a bracket, a laser, a camera, a controller and a vehicle, wherein the laser is arranged at one end of the bracket; the camera is arranged at the other end of the bracket; the controller is connected with the camera; one end of the bracket is connected with one side of the vehicle, and the other end of the bracket is suspended; an included angle between the laser and the vehicle is of a set value; the camera is used for acquiring road surface image information; the controller is used for acquiring an image distance from the vehicle to a round shoulder in the road surface image information, calculating the actual height from the camera to the road surface according to the image distance, the standard distance stored in the controller and the set value, and calculating the settlement value of the road foundation according to the actual height and the standard height stored in the controller; and by combination of linear information and the settlement value of a road passed by the vehicle, a road settlement change curve is generated, and full-automatic detection for the settlement value of the road foundation is realized. Therefore, the system and method provided by the invention have the advantage that the settlement value of the road foundation can be automatically detected.