The invention discloses a distribution network cable fault discrimination method and system using a grounding current signal. The distribution network cable fault discrimination method using the grounding current signal comprises the following steps: 1) selecting a typical distribution network cable line needing to be monitored in an emphasis manner, monitoring the grounding current of the typicaldistribution network cable line for a long time, and obtaining original data; 2) utilizing t-SNE to perform data mining and visualization processing on the monitored data to extract the characteristics of the original data, performs clustering analysis on the original data by using the DBSCAN, compares the classified non-periodic change rule abnormal cluster with the actual situation of the site,and establishes a knowledge base based on the characteristics of the grounding current; and 3) comparing the grounding current signals monitored in real time by using a knowledge base based on the grounding current characteristics, and updating the knowledge base according to on-site conditions to realize real-time discrimination of the state characteristics of the cable. The judgment of the distribution network cable is hardly influenced by the electromagnetic environment of the cable, and the result credibility is more accurate than the judgment result based on the threshold value.