The tool for detecting the verticality between an axle hole and a milling plane comprises a base provided with a horizontal plane and a vertical plane which are vertically intersected, a vertical through hole is provided, a locating plate is vertically arranged and located in the middle of the vertical through hole, the locating plate is fixed with the vertical plane, a horizontal through hole is provided on the locating plate, two vertical pin rods are arranged at a position of the base away from the vertical through hole, the vertical pin rods are symmetric with respect to the axis of the horizontal through hole, a detection rod can be inserted into the horizontal through hole.