The invention relates to a method for locating a disturbance source of an electrical power system. In the method, the disturbance is utilized to evaluate the fundamental positive-sequence impedance of a non-disturbance source side of the system, wherein the symbol of an resistance component in the impedance can reflect disturbance positions. At a dividing point M of a power-supply system side and a user side, the method is used to collect voltage and current waveforms containing the disturbance, and the power-supply system side is utilized as an upper stream and the user side is utilized as a lower stream; voltage changes and current changes generated by the disturbance at the M are respectively expressed as delta V and delta I, and the equivalent impedance of the voltage and the current is expressed as Ze; if the disturbance is generated at the power-supply system side, Ze is the equivalent impedance of the user side; if the disturbance is generated at the user side, Ze is a negative value of the equivalent impedance of the power-supply system side; and the symbol of a Ze resistive component is inspected to determine the direction of the disturbance source.