The invention provides a method for detecting and identifying constructional deficiencies of high-voltage and supervoltage cables and cable sets, which belongs to the field of power cable detection. Ameasurement unit conditions and acquires signals of a sensor and the signals are transmitted to an industry control computer by a USB communication mode. Software extracts various characteristic quantities of a discharge spectrum from local discharge signals and compares with a local discharge spectrum caused by the constructional deficiency of a prepared typical joint so as to judge whether an on-site running cable joint has deficiencies or not and judge the type of the deficiencies. The invention has the advantages that the method can carry out local discharge detection on electrified cablemiddle joints and effectively monitor insulated conditions according to the on-site requirement, thereby realizing the detection and the identification on the constructional deficiencies of the joints, providing scientific basis for the state maintenance of a cable system and improving the power supply reliability of the cable system.