The invention discloses a cable oscillating wave local discharge fault positioning system. The cable oscillating wave local discharge fault positioning system comprises a high-frequency current sensor; the high-frequency current sensor inputs a sensed local discharge signal to a presignal wave detector; the presignal wave detector judges the signal, and controls a subsequent variable gain amplifier to select direct connection or an amplification factor; then, the signal is amplified by the variable gain amplifier and then enters a high-speed AD collection card for AD conversion; and data are transmitted to an upper computer for analysis, processing and display. According to the cable oscillating wave local discharge fault positioning system, by increasing the presignal wave detector and the variable gain amplifier, an amplitude of a reflection signal is significantly improved, and an AD collection effect is improved; and meanwhile, correlation operation is adopted for sampled data andwaveform matching is performed on a waveform characteristic algorithm, so that a matching effect is improved to the utmost extent, an identification effect on the sensed signal in two times is greatlyimproved, and the fault positioning precision is effectively improved.