Abstract: The supercritical carbon dioxide power cycle exhibits performance advantages when operating under high-temperature conditions, and it has a good temperature matching with tower-type solar heat collection systems. The heat transfer and mechanical performances of the solar receiver during high-temperature operation directly affect the operational safety of the entire system. Therefore, ANSYS Fluent and ANSYS Mechanical software was used to investigate the thermal-mechanical performances of the solar receiver. Firstly, the influence of heat flux density distribution on the thermal-mechanical performances of the heat-collecting tube bundle was analyzed. Secondly, the tubes with poor performance in the circular tube bundle were replaced with enhanced tubes, and a comprehensive performance analysis was conducted on different types of tube bundles. Finally, the effects of different replacement schemes on the tube bundle performance were studied. The results show that: compared with the circular tube bundle, the total entropy generation of the internally ribbed tube bundle is reduced by 11.5% and the overall heat loss is reduced by 4.5%, while the equivalent stress of No.6 and No.12 tubes after replacement is reduced by 14.9%. The 5-6-7-11-12-13 tube bundle achieves the optimal comprehensive performance—its total entropy generation is reduced by 44.7%, the overall heat loss is reduced by 25.2% compared with the circular tube bundle, and the maximum equivalent stress is lower than that of the circular tube bundle. This study provides a theoretical basis for the design and optimization of solar cavity receivers.