Deformation behavior of endangered earthen heritage slope makes sense to scientific conservation of earthen architecture. It realizes qualitative and quantitative description of diseases. Based on random process and description theory, deformation behavior of endangered earthen heritage slope (Jiaohe Ruins) is studied using high-accuracy, real-time, dynamic information obtained by deformation monitoring appliance. Research result indicates that mathematic model can be established by use of modern mathematic method. The mathematic model of Jiaohe slope proves that short-term deformation behavior owns periodicity (36h) and occasional mutation. Simultaneously, tendency deformation performs weakly. The conclusion lays foundation for the research on quantitative deformation behavior and the following forecasting of similar earthen heritage slope damages.