Abstract: A device for thermal insulation performance of high-temperature materials was designed and established to test light mass thermal insulation materials via a rapid and simple procedure. The thermal insulation performance of carbon fiber/phenolic composite and ZrO₂ fiberboard were tested by this device when the temperature at the center point of hot face was 1600℃±10℃. The heat transport process of ZrO₂ fiberboard was numerically simulated by finite-difference method, and the effective thermal conductivity was also predicted. The results show that thermal insulation performance of carbon fiber/phenolic composite is better than that of ZrO₂ fiberboard from the beginning of test to 400s, while the thermal insulation performance of ZrO₂ fiberboard is better from 400s to the end of test. Thermal insulation performance of ZrO₂ fiberboard is affected by the bulk density, and the effective thermal conductivity of ZrO₂ fiberboard increases nonlinearly with the elevated temperature.