Abstract: Magnetic pole coil of the motor-generator for 300 MW unit in Inner Mongolia Hohhot Pumped-Storage Power Station uses the radial fixation mode with the steel platen fixed by the countersunk screw and coil pressed by the steel platen. The insulation pressure plate of the fixed magnetic pole coil is loose during the maintenance of the unit. The fixed mode of the insulation blocks (T shaped blocks) at the upper and lower ends of the magnetic pole coil is changed from the radial mode to the axial one to eliminate the hidden trouble of the countersunk screw.