<p>In order to exactly master the effect of gradient heat shield on temperature field in the vacuum sintering furnace, a three-dimensional thermal model was established according to the theory of heat conduction and radiation, as well as the actual operating conditions of the furnace during reaction sintering of silicon carbide (RSSC). The effect of thermal shield on the temperature distribution and heat absorbed ratio was investigated by orthogonal experiments. The optimized thermal shield structure improves temperature uniformity in the furnace, reducing the maximum temperature difference of single workpiece by 51.6% and increasing the workpieces heat absorbed ratio from 25.31% to 33.28%. A collaborative optimizing model for thermal resistance and radiation and a correction factor of complex curved structure were proposed to explain the mechanism of enhanced energy efficiency by the gradient thermal shield, providing a theoretical basis for its structural optimization.</p>