The invention discloses a cable insulation defect identification and positioning method and system. The method comprises the steps that gradiently increased frequency signals are injected into a to-be-detected cable; a voltage signal and a current signal corresponding to each frequency signal are acquired from an injection position; according to the gradiently increased frequency signals and the voltage signal and the current signal corresponding to each frequency signal, an impedance spectrum of the to-be-detected cable is acquired; whether an insulation defect and a positioning defect position exist in the to-be-detected cable or not is identified according to the acquired impedance spectrum. According to the method and system, a test can be carried out without damaging the cable, and secondary damage to the cable is avoided; the test is not limited by the length of the cable, technical bottlenecks of fault positioning and aging evaluation of long-distance cables are broken through,and integrated detection and evaluation of a plurality of connected cables are achieved. The method and system can be used for accurate fault positioning, multi-point accurate positioning can be realized, a plurality of defect points can be found conveniently, and the severity degree of different defect points can be evaluated.