Surface whitening of earthen sites, a phenomenon often occurs in dry environments, is closely related to the humidity of the site. The Han Yang tomb underground exhibition hall is the first fully - enclosed exhibition hall in China. Although the exhibition hall of pit No. 13 has a constant humidity of 100%, surface whitening is still heavy in this high humid site. To better understand the causes of whitening, and the sources of the white materials, X - ray fluorescence spectroscopy, Fourier transfer infrared spectroscopy, X - ray diffraction and ion chromatography were used to analyze the elements, ions and phases of surface white materials in pit No. 13. The results of these studies show that the white material is mainly gypsum (CaS04 • 2H20). The results of ion chromatography suggest that migration and enrichment of soluble salts in soil may be the cause of the whitening.