A pneumatic spanner structure includes a head body, a link bevel gear unit, a hit unit and a driving handle. A driving motor axle portion at an open end of the driving handle drives a motor link bevel gear post and a hit unit link bevel gear plate of the link bevel gear unit. The hit unit link bevel gear plate links the hit unit. The link bevel gear unit enhances and transmits the force to the hit unit. The hit unit applies the acting force on a workpiece. The hit unit doesn't need a buffer space for actuation and the force is indirect. The link bevel gear unit is a deceleration device to extend the service life of the whole structure. The output force is more powerful than the prior art, providing a stable and compact structure.