Abstract: To address the thermal protection requirements of high-speed, high-temperature two-dimensional nozzles in ground test facilities, a numerical study on active cooling performance under various operating conditions was conducted. Rectangular cooling channels perpendicular to the airflow direction were designed within the wall panels to investigate the effects of different cooling configurations on wall temperature distribution, wall heat flux distribution, and exit Mach number distribution. The results indicate that localized cooling significantly reduces the maximum throat temperature from 469.1 K under adiabatic conditions to 372.5 K, effectively decreasing the wall temperature in the throat region and improving temperature uniformity. While global cooling enhances the uniformity of wall temperature distribution and reduces thermal stress within the wall panels, it adversely affects the downstream temperature and velocity boundary layer thickness, leading to a deterioration of Mach number uniformity in the core flow region and a degradation of flow field quality.