Nowadays,using a solar-driven thermochemical reaction system to convert greenhouse gases into high-quality liquid fuels has been proven to be an effective way to address the growing depletion of traditional fossil fuels.However,the utilization of highlyconcentrated solar irradiation runs the high risk of reactor damage issues resulting from thermal stress concentration,which seriously threatens the security and reliability of the total reactor system.In this study,the thermal radiation distribution and thermo-mechanical process in a volumetric reactor were numerically investigated by combining Monte Carlo ray-tracing method with computational fluid dynamics method.Based on the experimental results and thermal characteristic analysis,the formation mechanism of thermal stress concentration and the strategies of improving thermal stress distribution were discussed in detail.The simulation results indicate a great possibility of reactor damage at about 1000℃ operating temperature and 9.0 kW lamp power,which is well-matched with related experimental results.The ceramic damage typically occurs at the inner edges of the through-holes,including the aperture,the gas inlet,and the thermocouple hole,then extends along the lines connecting these holes and finally causes brittle fracture.By reasonable control of the opening direction and the distance between the throughholes,the maximum compressive stress can be reduced by 21.78％.