The utility model discloses an automobile wheel hub presses pneumatic ejecting device of bearing inner race, including backup pad and cylinder, article two, the cylinder sets up respectively on the ears seat of operation panel both sides support, the cylinder push rod top of every cylinder is rotated with the both ends bottom of backup pad respectively and is connected, and wherein the cylinder push rod of one end is connected through semi -circular activity latch segment with the backup pad, semi -circular activity latch segment upper end is for the sphere and be located the backup pad, be provided with a plurality of uide bushings in the backup pad, run through the guide post that has AND operation platform fixed connection in every uide bushing respectively, run through the lower pressure head that has with control console connection in backup pad center part's the round opening, there is the tray pressure head periphery through the spring -supported down, and the diameter of tray is greater than backup pad center part round opening's diameter, the well core rod upper end at the vertical center of pressure head is run through down has last pressure head. The utility model discloses during the use, after preceding wheel hub pressure equipment is accomplished, drive the backup pad through two cylinders and hold out preceding wheel hub, reduce worker intensity of labour.