To locate the fault point of twisted pair in voice communication is of great significance for the detection of open circuits, short circuit faults, and the prevention of eavesdropping on confidential information. In the fault detection and localization of voice communication twisted pair based on time domain reflectometry (TDR) and spread spectrum time domain reflectometry (SSTDR), due to the low-frequency transmission characteristics of twisted pair, the reflected signal is seriously attenuated, and long-distance fault point location cannot be realized. Given this problem, a time-frequency domain reflectometry ( FRFT-TFDR) based on fractional Fourier transform is proposed. First, the chirp signal (LFM) is used as the detection signal, the received signal is windowed to improve the resolution of the signal, then the fractional order Fourier transform is performed to transform the received signal into the fractional domain. Finally, the position difference of incident signal and reflected signal spectral peak in the u domain is analyzed and converted into the time domain, so that the location of errors can be determined. The experiment verifies that the method can effectively locate different circuit-breaking fault points, and its positioning error at 1 557 meters is less than 7%, meeting the requirement of remote fault detection of twisted pair in voice communication.