Abstract: Micro reactors, typically with power below 15 MW, are designed in a modular fashion, allowing for flexible and maneuverable deployment, enabling independent operation away from the grid. They can meet energy demands in various scenarios such as remote areas, isolated islands, and desert regions. These reactors hold potential application value and strategic significance in scientific. Supercritical carbon dioxide (SCO₂) Brayton cycle, with its high cycle efficiency, high capacity-to-power ratio, and compact structure, has excellent prospects in the field of nuclear power. It is well suited as an energy conversion system for micro reactors. Scholars both domestically and internationally have conducted extensive research on this topic. In this study, different configurations of SCO₂ Brayton cycle systems were investigated. The system-component combined design method was applied, which combined the cycle thermodynamic model with the component design method to iteratively correct the cycle thermodynamic calculations and component design results. Equipment models and overall system analysis models were established, and key components were selected and thermally designed. Optimization of system parameters for different configurations was carried out using various evaluation criteria, resulting in the identification of the optimal configuration and parameter settings for different optimization objectives. The results indicate that for the SCO2 Brayton cycle in micro reactors, the system design scheme including heat pipe reactors, centrifugal turbines, centrifugal compressors, shell-and-tube main heat exchangers with heat pipes, printed circuit board recuperator, and flat finned-tube coolers is deemed reasonable. When maximizing power generation efficiency as the optimization objective, the optimal cycle configuration is the recompression-heating-reheating cycle (RHRC), achieving a maximum power generation efficiency of 47.5%. When maximizing power density as the optimization objective, the optimal cycle configuration is the recompression cycle (RC), with a maximum power density of 282.42 kW/m³. When maximizing power-to-mass ratio as the optimization objective, the optimal cycle configuration is also RC, with a maximum power-to-mass ratio of 98.81 kW/t. Through a comparison of different configurations, it is found that the RHRC configuration exhibits higher efficiency, but it also has a larger system volume and mass. The RC configuration has efficiency close to the RHRC configuration while possessing higher power density and power-to-mass ratio. It effectively balances efficiency and compactness, making it more suitable as a mobile micro reactor energy conversion system.