The invention relates to a high precision gyro motor bearing loading method. The loading can be achieved by using of a gyro motor loading device, and the gyro motor loading device consists of a machine frame, a platform surface, a horizontal guide rail system, a lifting guide rail system, two displacement sensors, an air bearing support, weights, an air shaft, a bearing centering sleeve and a bearing centering base. The centring can be achieved through a shaft at one end of the gyro motor, and the positioning can be achieved on an outer ring of a bearing, weights are placed in a weight plate, and required loads (namely, preloads) are added on an outer ring of a bearing at the other end through the air bearing. Then the size between two sets of bearing outer ring shaft shoulders is measured with a method of differential measurement through a displacement sensor 1 and a displacement sensor 2 which are calibrated. The height size of an outer rotor of the gyro motor is matched according to the measured size, and the post-installed preload of the gyro motor is guaranteed. The loading precision is greatly improved, errors caused by that the loading force does not pass through the center line of the motor bearing are eliminated, and the displacement measurement accuracy is improved.