Conservation of steep earthen slope sites is different from that of common earthen slopes. For high, steep slope in danger of crumbling, the most common treatment is to remove part of the tip and to patch the base. However, an important aim of protecting earthen slopes of cultural heritage interest is to preserve their current appearance, so conservation of such sites poses some special problems. The process of deformation of steep earthen slopes has some unique characteristics. An automatic deformation monitoring instrument with an accuracy of 0.01 mm was installed at the Nanrui dam in the 51 - 3 sub region of the Jiaohe ruins to gather real- time data on a conserved earthen slope that is in danger of crumbling. Analysis of the data obtained revealed the characteristics of the deformation and the evolutionary process of this deformation. The results indicate that the conserved slope deforms nonlinearly. Parts of the slope change normally and steadily, and other parts deform abnormally and rapidly. Deformation trends could also be observed, namely, periodical vibration deformations and random deformations. The research is of importance for the evaluation of enhancement of similar earthen slope sites.