The drying and moisture removing of three-phase asynchronous explosion-proof motor ( rated power 710 kW ) of rotating axial flow main fan in Beishigou shaft of Du’erping Mine was taken as example, high - voltage motor adopting self - coupling transformer for drying treatment was introduced, including determining the degree of dampness, the current and temperature the motor stator windings, the power supply and wiring method. The result showed that the drying method was suitable for the drying of large induction motor, with effective drying.