In order to maintain the temperature of the reentry capsule, the S781 thermal coating is painted on
outside wall of the reentry capsule of manned spacecraft. In the painting process, the color difference appears between
the partition and adjacent partition. In this paper, the composition of color difference area of S781 coating is analyzed,
and several experiments are designed with different painting temperatures, interval time and materials. The result
reveals that the color difference is due to that the interval time of partition painting is longer than the surface drying
time of the coating. The color difference becomes obviously with the interval time, which is more than 1 minute.
And there are granules when the temperature is high, because the surface dries much more quickly. At last, an improved
painting method of S781 thermal coat is proposed to control the joint color difference. The result will be helpful
to the implement of thermal control of manned spacecraft.