In order to solve the problem of mine shaft drench water freezing in winter, frequency conversion air heating unit in the wellbore antifreeze was applied to calculate the heating load of unit and introduces air heating way, the frequency conversion air heating function, structure and operation of the unit was described. The frequency conversion air heating units and common air heating unit investment cost and energy saving were analyzed. The practice proved that frequency conversion air heating unit heating effect was good, the energy saving was obvious.