The invention disclose a detecting device for the verticality between a top surface and an end surface of a lead rail, which includes a locating plate and a dial indicator mounting piece; the locatingplate includes a side part and a connecting part which mutually form an L shape; the dial indicator mounting piece is a T-shaped structure; a T-shaped vertical is fixed on the connection part; a T-shaped transverse part is vertical to a side panel; the two end parts of the T-shaped transverse part are provided with dial indicator mounting structures; the side of the side part facing to the connection part is respectively provided with an end surface locating column butted with the end surface of the vertical part of a T-shaped lead rail, a top surface locating column butted with the top surface of the vertical part of the T-shaped lead rail as well as a side surface locating bead. The detecting device for the verticality between the top surface and the end surface of the lead rail is assembled by a plurality of parts; compared with a welding piece, the detecting device for the verticality between the top surface and the end surface of the lead rail has a beautiful appearance and is conveniently processed; the opposite height positions of the locating plate and the dial indicator arranged on the dial indicator mounting piece can be adjusted within a certain range, thus being capable of leading the device to be applied on the lead rails with different types, have high adaptation performance and save cost for the enterprise.