High-voltage underground cable systems are one of the critical systems used in the distribution of energy. During the design phase of these systems, important issues are to be considered, such as screen voltages, screen currents, thermal calculations, and power losses. If these issues are not considered properly, the system's reliability and efficiency can be seriously reduced. In high-voltage underground cable systems, current carrying capacity and power losses vary according to the screen bonding type, the phase sequence, the distance between the cables, and the number of parallel systems. A detailed analysis is required during the system design phase in this context. In this study, electrical and thermal analyses of a cable system consisting of two parallel group were carried out according to different design parameters, and the performances of different system designs were evaluated. Trefoil and flat layouts were used in the analyzed systems. In addition, the structure of the single-side and solidly bonded systems was also examined. While carrying out the investigations, the variation of the distance between the cables according to three different parameters was also discussed. In total, 56 different scenarios were created, and the systems’ performances were examined. Screen currents, screen voltages, cable temperatures, and power losses were considered while conducting the investigations. In this context, coupled electrical and thermal calculations were performed in the Ansys Electronics Suite finite element software. Additionally, the study utilized the CymCap program to verify the finite element model created, with analytical analyses conducted in accordance with IEC 60287 standards. The significance of these calculations cannot be overstated, as the analysis results demonstrate the direct impact of various design parameters on the system's overall performance.