Abstract: The loess occurs as a special kind of earth on a wide range of scales in Ningxia, China. However, little was known before about the importance of the loess in the construction of highways in the loess areas. The present paper deals with physical and chemical properties, especially the self-collapsibility of the loess along the HeichengHaiyuan Expressway in Ningxia on the basis of relevant engineering experimental data. The results of research may improve our knowledge of engineering geology of the loess and will assist in the construction of highways in the loess area.