The invention provides an online correction method for structural errors of space phase modulated toroidal traveling wave ultrasonic motor based on detecting amplitude deviation and space phase deviation which caused by structural errors of the motor. The method utilizes the capacity of the motor to generate standing wave with different space phases and different amplitudes to remove or compensate the amplitude deviation and the space phase deviation, so as to correct standing wave components in the stator caused by structural errors. The method based on rational selected correction mold of amplitude deviation(Delta c) and correction mode of space phase deviation(Delta x) keeps the output as large as possible when the structural errors in the space phase modulated toroidal traveling wave ultrasonic motor is corrected, and keeps the maximum voltage amplitude of the four-phase motor as small as possible. The method has the advantages of ensuring the consistency of output characteristics after correction, while reduce the requirements of the correction scheme in the ceramics withstand voltage of the motor.