The invention discloses a gear rack meshing type motor end cover end surface run-out measuring device which comprises a base, a first screw rod, a left clamping hand, a right clamping hand, an inner gear disc, a driving motor, a center gear, a planetary gear and a run-out table, the left clamping hand and the right clamping hand are respectively welded on the upper sides of a first sliding block and a second sliding block, and the planetary gear is connected between the center gear and the meshing teeth at the inner edge of the inner gear disc in a meshed mode, a connecting shaft is arranged at the gear core of the planetary gear in an interference fit mode, and the run-out table is fixedly connected to the lower end of the connecting shaft. According to the measuring device, the end covers with different diameters can be clamped, and the universality of the device is greatly improved; rubber protection pads are arranged on the inner sides of the arc-shaped clamps on the left clampinghand and the right clamping hand, so that the electrophoresis layer on the surface of the end cover is effectively prevented from being damaged when the end cover is clamped; and by means of the planetary type rotation, the run-out table performs circular motion, and can run stably in the circular motion process, so that the run-out detection is more accurate.