To ensure safe operation of instrumentation and control (I&C) cables in nuclear power plants (NPP),time-frequency domain reflectometry (TFDR) is widely applied to identify and locate typical defects in I&C cables. The advantages of Wigner-Ville distribution (WVD),pseudo Wigner-Ville distribution (PWVD),and smooth pseudo Wigner-Ville distribution (SPWVD)are compared. In addition,the energy range scaling method is proposed in the time-frequency cross-correlation (TFCC) processing. During the experiment,a 50-meter and a 148-meter multi-core cross-linked polyolefin I&C cable are prepared to simulate several failure cases,including short circuit,open circuit,metal shield damage,and local thermal agingdefect. Based on the TFDR method,three time-frequency distribution algorithms are adopted. Then,the energy range scaling method is applied to improve the problem of wide main lobe of TFCC localization peak. The experimental results show that the main lobe of TFCC is wider after SPWVD processing. PWVD has a better inhibitory effect on cross terms in normal cable detection. In terms of detecting a defect,SPWVD has better detection ability. By using the energy range scaling method,similar localization peaks can be separated to enhance the discrimination of weak reflection signals.