The present application discloses a wheel brake space detecting device comprising a frame, a first servo motor, a connecting shaft, a pedestal, a rotating shaft, a rotary cylinder, a first bearing, a first bearing end cap, a base, a second bearing, a second bearing end cap, a shaft, a shaft sleeve, contacts, a spring, linear bearings, a synchronous cam, a probe, a probe holder, a first sliding frame, a first lead screw nut, a first guide rail sliding seat, a first linear guide rail, a first ball screw, a second servo motor, a suspension, a second linear guide rail, a second guide rail sliding seat, a second lead screw nut, a second ball screw, a third servo motor, and a second sliding frame.