The invention discloses a detecting device for a belt surface of a conveyer belt and a detection method thereof and belongs to the technical field of conveyer belt detection. The detecting device for the belt surface of the conveyer belt comprises an image scanner 1, a supporting frame 2, a dust cleaner 3, a switch 5, a power source and a controller, wherein the image scanner 1 is mounted on the supporting frame 2; the supporting frame 2 is arranged under the conveyer belt 6; the switch 5 is connected with the controller; the dust cleaner 3 is mounted on the front side of the image scanner 1 and is fixed on the supporting frame 2; the conveyer belt 6 passes through the dust cleaner 3 and then passes through the image scanner 1; the dust cleaner 3 is connected with the power source and is supplied with power by the power source for cleaning the conveyer belt 6; and the power source is connected with the controller. The detecting device provided by the invention is used for solving the problems in the prior art that the surface abrasion condition of the conveyer belt is unknown and a specially-assigned person is required for reviewing. The detecting device has the advantages of real-time detection and display convenience. The detection analysis result for the conveyer belt can be directly displayed, no specially-assigned person is required for reviewing and even the early warning for a belt broken phenomenon can be realized.