The invention discloses a middle and low voltage cable insulating part aging testing method, and the method is characterized in that a cable comprises a shielding line unit, an insulating line unit, a grounding line, an external shielding sleeve, and an insulating part; the insulating part is disposed outside the external shielding sleeve; the shielding line unit, the insulating line unit and the grounding line are twisted together in the external shielding sleeve; the method comprises the steps: 1, selecting at least three cable samples with the same length from the tested cable; 2, enabling the cable samples to be placed in a test room with the temperature being constant temperature; 3, measuring the resistance values of the insulating parts of the cable samples when the temperature of the cable samples is consistent with the temperature of the test room; 4, calculating the mean resistance value of the insulating parts of the cable samples, and enabling the mean resistance value to be compared with a critical resistance value, so as to judge whether the insulating part of the cable is aged or not. The method simplifies the process of cable insulating part aging, and improves the detection efficiency.