The invention discloses a method for judging the fault direction of a power distribution network with an inverter power supply. The method comprises steps that the access position of the inverter power supply is determined, so the minimum short-circuit current provided by a power system is constantly greater than the maximum short-circuit current provided by the inverter power supply; a phase angle of the positive sequence fault component measurement impedance at the protection installation position is calculated; if the phase angle is in a range of greater than-135 DEG and less than-45 DEG, that a fault is a protection positive direction fault is determined; if the phase angle is in a range of more than -45 degrees and less than 0 degree or the phase angle is in a range of greater than -180 degrees and less than -45 degrees, the measured current at the protection installation position is compared with the maximum short-circuit current provided by the inverter power supply; the fault direction is determined through comparison of current amplitudes. The method is advantaged in that sensitivity of judging the fault direction at the junction of the positive direction fault and the negative direction fault is improved.