The invention relates to a mechanical resonance suppression method for an electromechanical servo system based on an extreme value search algorithm, which belongs to the field of mechanical resonancesuppression for an electromechanical servo system and solves a problem that the existing adaptive notch filter based mechanical resonance suppression method is poor in real-time performance. The mechanical resonance suppression method is characterized in that the extreme value search algorithm is introduced into the design of an adaptive notch filter, a cost function is built based on the output signal amplitude of a band-pass filter, a recognition problem for the mechanical resonance frequency is converted into an maximum value search problem for the output signal amplitude of the band-pass filter, a cost function is built based on the output signal amplitude of the notch filter, a resonance suppression problem is converted into a minimum value search problem for the output signal amplitude of the notch filter, a width parameter and a depth parameter of the notch filter when the output signal amplitude is the minimum and the recognized mechanical resonance frequency are enabled to respectively serve as a width parameter, a depth parameter and a center frequency of a notch filter unit additionally arranged in a controller, and the electromechanical servo system is controlled through the controller.