The invention discloses a local-discharge time-frequency mixing characteristic parameter extracting method for ultrahigh-cable cables. By the local-discharge time-frequency mixing characteristic parameter extracting method, ascending and descending time of a current pulse, pulse width and height, power, negative pulse return time and pulse duration time can be obtained. Compared with those extracting characteristic parameters by common time domain parameters or frequency spectrum parameters only, the local-discharge time-frequency mixing characteristic parameter extracting method introduces accurate time domain characteristics and fractal dimension and corrected cepstrum characteristics, can resist to effects of cable transmission signal channels on the characteristics, is higher in efficiency and accuracy and has excellent application prospect.