To achieve the best living effect, the ancients used their accumulated experience to decorate and transform the interior of houses. This paper analyzes the white surface of F33 and F50 at the Hamin-Mangha site in Tongliao, eastern Inner Mongolia. It is found that the reason for the hard and white ground of the site is the use of white ash as the ground decoration layer; The change of infrared spectrum peak in absorption intensity is used to judge the information of atomic disorder in calcium carbonate, to judge its manufacturing process. The results show that the ratio of calcite ν2/ν4 in the white bedding material of the site is about 5, which is much higher than that of natural limestone, which reflects the difference in the disorder of calcite crystal structure between natural limestone and artificially prepared lime mortar. It proves that the white ash layer of the site is artificially fired, indicating that our ancient ancestors began to use artificially fired lime as decorative building materials a long time ago.