The detection and repair of cable faults can provide a powerful guarantee for the continuous and high-quality supply of electricity, especially the detection of soft faults in cables can prevent system accidents and is of great significance in maintaining the stability, safety and reliability of system operation. The detection and location of hard faults in cables is no longer a technical challenge, but the detection of soft faults in cables is still a major challenge, especially as the problem of loss compensation in actual cables has been the key to the detection of soft faults. Therefore, in this paper, the loss of the actual cable is studied in depth to understand the process of signal attenuation. The method of attenuation compensation for the scattering parameters of the actual cable is put forward, and the application of the soft fault detection method based on the inverse scattering theory in the soft fault detection of the actual cable is realized. The actual soft fault model of the cable was designed using RG58-SYV-50-3 type coaxial cable. It was used to verify the effectiveness of the cable soft fault detection method based on the inverse scattering theory in the detection of actual cable soft faults.