The invention discloses a fool-proof universal cage dismounting detection tool including a pedestal, a cage and a dismounting detection tool. A clamping mechanism is fixedly mounted on the pedestal. A bell housing of the cage is clamped on the clamping mechanism. A plurality of height-adjustable support posts are mounted on the periphery of the clamping mechanism and on the pedestal. An annular guide rail is mounted at the tops of the support posts. The dismounting detection tool includes a straight handle, a bow-shaped handle and a spline head. The bow-shaped handle is connected to the front end of the straight handle integrally. The spline head is mounted on the outer side of the front end of the bow-shaped handle and engages with internal spline of a star-shaped housing of the cage. The straight handle can rotate along the inner edge of the annular guide rail, centering the spline head. The tool provided by the invention is simple in structure, stable in functions and can realize fool-proof performance and error correction and can also realize stepless switching of swinging angles of the cage. The tool provided by the invention is an ideal cage dismounting detection tool.