Abstract: In order to analyze the influence of different conditions on the temperature of the test piece in the high temperature test environment, a heat transfer model is established for the high temperature test environment. The method of the computational fluid dynamics (CFD) combined with the Discrete Ordinates (DO) radiation model is used to calculate and analyze the temperature distributions when the test piece is heated by the quartz lamp heater. The isothermal boundary conditions are adopted, and the calculations are carried out for different heat source temperatures, different specimen sizes, and for a surrounding heat insulation layer with and without a reflective coating, respectively. The simulation results show that: with the same heat source temperature, the temperature of the specimen under the heat insulation layer with reflective coating is 18% higher than that of the specimen under the heat insulation layer without reflective coating. Due to the boundary effect, the surface uniformity is over 14% for the large-scale specimen, while it is less than 1% for the small size test piece. The heat flux is required to be 1122 kW/m² for raising the temperature of the test piece to 1500 ℃ within 150 s for the test piece of a small size and surrounded by the insulation with reflective coating. The above results can be used for the design of the high temperature environmental simulation test bed.