Complex laying environments and external electromagnetic interference have significantly impacted the accuracy of cable fault location, particularly in modern power grids with the widespread application of cross-linked polyethylene (XLPE) power cables. In order to solve the low accuracy of existing fault location methods in high-noise environments, an improved fault positioning method based on spread spectrum time domain reflectometry (SSTDR) is proposed. Firstly, by introducing a multi-period signal modeling method using M-sequences, combined with windowed filtering and adaptive wavelet denoising, the reflected signals are optimized. Subsequently, a quadratic cross-correlation weighting method based on the smoothed coherence transform (SCOT) weighting function is employed to process the incident signals and the filtered reflected signals for each period, obtaining the correlation coefficients for each period. The final location information is derived through arithmetic averaging. Finally, Gaussian smoothing filtering is applied to enhance the peak characteristics of the fault location, and the fault position is determined using a peak detection algorithm. Simulation experiments conducted on the MATLAB/Simulink platform demonstrate that under a low signal-to-noise ratio of -20 dB, the average location error for short-circuit, open-circuit faults at different positions, and multi-branch faults is less than 0.062 m, with an average relative error below 0.25%. Compared to traditional methods and existing methods, the proposed method exhibits effective localization under low signal-to-noise ratio conditions, with the relative localization error improving by at least 0.01%. Furthermore, the experimental results validate that the method proposed in this paper has robust noise-resistant fault localization performance.