Abstract—Temperature is one of the primary causes of medium voltage cable failures. When the temperature exceeds the allowable limit, the cable components may degrade, affecting the lifespan and operational efficiency of the power system. In order to maintain the safe operation of power systems and minimize the likelihood of severe accidents, it is crucial to analyze the temperature distribution in medium voltage underground cables. In this study, the time-dependent temperature distribution within the 5.5 mm thick Cross-Linked Polyethylene (XLPE) insulation layer of medium voltage cables is analyzed using the finite element method. Temperature data collected from the cable sheath surface is utilized to simulate the thermal variation in cable insulation layer under the varying of core current and sheath temperature. Additionally, a temperature warning threshold is calculated to issue alerts and prevent overheating. The variations in the electric field under these conditions are also examined. The results provide valuable insights for optimizing the installation and operation of medium voltage power cables.