Convection heat transfer distribution on a high-temperature rotating disk in a horizontal air flow duct was analyzed by three-dimensional computational fluid dynamics (CFD) code. The temperature of the disk was 1000°C, and the rotation speed was 60–480 rpm. The temperature of the inlet air was 25°C, and the velocity was 0–1 m/s. The air flow pattern was affected by natural convection caused by temperature difference, forced convection flow along the disk surface, rotation flow induced by the disk, and volume expansion of gas. The calculated results show that the ratio of the maximum and minimum values of the average heat flux along the circumstance direction on the disk was large when the rotation speed and air velocity were small.