Abstract: The formation and development of undercutting area is one of the typical diseases controlled by climatic factors and will commonly and directly do harm to earthern ruins in arid region. Based on the results of feature description and salinity monitoring of undercutting area in some typical relics in Turpan Gaochang ancient ruins, Guazhou Suoyang ruins, Yinchuan Xixia King tomb and Xining Ming Great Wall, it is found that aeolian bond exists in the bottom undercutting area of earthern ruins. Based on the results of wind tunnel and elastic wave velocity experiments in laboratory on remodeling samples mixed with different salt contents and undergoing three dry-moisture cycles after desalination, it is revealed that salinized deterioration and aeolian ullage are two important effects in the process of the diseases. In-depth analysis and interpretation of mechanism of disease are performed so as to discover influences of salt type, salt content and wind velocity on the two effects. Through engineering geology and mechanical theory analysis, three categories of deformation and failure mechanism of evolution due to ruin’s undercutting are summarized. It may be useful for controlling and monitoring the disease and its impact on stability of ruins.