The invention discloses a power cable fault locating method and system. The method comprises the following steps: acquiring the head-end current, tail-end current, head-end voltage and tail-end voltage of a failed power cable; calculating the line surge impedance of the power cable according to the head-end current, the tail-end current, the head-end voltage and the tail-end voltage of the power cable; calculating the line transmission coefficient of the power cable according to the head-end current, the tail-end current, the head-end voltage, the tail-end voltage and the line surge impedanceof the power cable; and calculating the distance between a fault point and the head end of the power cable according to the line surge impedance and the line transmission coefficient. Through adoptionof the power cable fault locating method and system disclosed by the invention, the distance between the fault point and the head end of the power cable can be calculated more accurately, and the fault point locating accuracy is improved.