The invention relates to the field of automobile polishing, and relates to an automobile automatic polishing device. The automobile automatic polishing device comprises a ramp. The ramp is connected with an abutting block and a sliding table, and the sliding table is connected with a first motor and a negative pressure machine. The first motor is connected with a bevel gear and a turbine, and thebevel gear meshes with an incomplete bevel gear. The incomplete bevel gear is connected with a second rotating shaft, the second rotating shaft is connected with a bracket and a supporting plate, andthe supporting plate is provided with air holes. The turbine meshes with a worm, and the worm is connected with a winding wheel. The rewinding wheel and the abutting block are connected, and the negative pressure machine is connected with the second rotating shaft. The sliding table and the bracket are connected with a first spring. The ramp is connected with a supporting frame, the supporting frame is connected with a grinding motor, and the grinding motor is connected with a hollow shaft. The hollow shaft is connected with a supporting rod, the supporting rod is connected with a universal joint, and the universal joint is connected with a polishing head. The automobile automatic polishing device solves the problems of uneven surface polishing and poor polishing effect after manual polishing of a bumper in the prior art.