The invention discloses a method and system for controlling a respirator through impedance cardiography signals. The method comprises the steps that in the external chest compressing process, the impedance cardiography signals of a patient are obtained through a defibrillating electrode and digitally acquired, and the acquired impedance cardiography signals are processed; the differential signal of the impedance cardiography signals is calculated, and variation of the impedance cardiography signals and the differential signal are comprehensively analyzed; pressurizing periods and relaxing periods of external chest compression are identified in real time by setting detection threshold values, and detection results are simultaneously fed back to the respirator; by means of the feedback results of the impedance cardiography signals, the respirator is controlled to inhale in the relaxing periods and to exhale in the pressurizing periods in the continuous external chest compressing process, synchronous aeration of external chest compression is achieved, hyperventilation or hypoventilation is avoided, the resuscilation successful rate is increased, and a rescuer can operate the respirator more standardly.