Many studies have shown that the semi-conducting layers (SCL) can have significant impacts on high-frequency (HF) wave propagation in power cables. Therefore, knowledge on the characterization of SCL materials is essential to establish the accurate cable model for HF technique application, such as partial discharge (PD) diagnostics, power line communication (PLC) and so on. Unfortunately, the dielectric characteristics of SCL in XLPE cables are usually unknown and hard to measure. Previous works on the characterization of SCL in XLPE cables by Mugala etal have achieved good performance in frequency domain. However, direct measurement on the dielectric properties of SCL is still a trough work, which needs specialized testing platform and making proper samples. What is more, the SCL samples are usually not available especially for an installed cable. To address this issue, based on the T-section circuit model(See Figure 1) proposed in this work, an simulated annealing (SA)-based optimization approach is developed.