As a novel form of energy storage, large-capacity flywheels offer a promising solution for supporting the efficient operation of new energy grid connection and advanced power system. In order to ensure the stable operation of the flywheel rotor, the introduction of superconducting maglev bearings (SMB), characterized by stable levitation without the need for an origin, low energy losses, and high rotational speeds, can significantly enhance the performance of large-capacity flywheel. This paper focuses on a 100 kWh flywheel energy storage system, where the axial load requirement for the heavy-duty bearing system is set at 8 tonnes. A rotor-excited SMB system is designed, with reference to the stator-excited SMB designed by the Japan Institute of Iron and Steel Technology (ISIT), to investigate the levitation performance of both SMB configurations at different temperatures. Furthermore, the levitation force and stiffness are calculated under optimal parameter combinations to compare the mechanical performances of the two configurations. The mechanical properties of the bearing system are compared. The results reveal that, due to structural differences, the rotor-excited and stator-excited SMBs exhibit distinct levitation characteristics and mechanical properties, each offering specific advantages and disadvantages for the operation of large-capacity flywheels. These findings provide valuable insights and solutions for further performance optimization of such systems.