Abstract: To meet the thermal protection requirements of high-speed and high-temperature two-dimensional nozzles in ground test facilities, a numerical study was conducted to evaluate the active cooling performance under different operating conditions. 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 indicated that localized cooling significantly reduced 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 enhanced the uniformity of wall temperature distribution and reduced thermal stress within the wall panels, it adversely affected 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.