Abstract: In this paper a reciprocity method of calibrating electromechanical transducers and seismographs by external mechanical loading reactance is discussed. It gives a description of the principle of the method and then its applications in calibrating an electromechanical transducer and an electromechanical seismograph produced by the Peking Shunhu Vibration Instrument Factory. The results agree quite well with that given by calibration on shaking table.