Abstract：Landslide prediction is one of the hot issues in the field of engineering geology，but the relevant theories have not been well built up so far. Combining the experience and lessons from the practices of the several cases of slope prediction and monitoring in recent years，the three-phase law of landslide deformation with time and assorted characters of cracks spatial evolution in different deformation periods，and the effects of the external factors on the evolution of slope deformation are analyzed. The following results are drawn. (1) The slope deformation experiences three stages in time，i.e. initial deformation stage，constant deformation stage and accelerative deformation stage；and the correct prediction of slope deformation stage is the basis of exact landslide prediction. (2) The cracks on the ground surface will form a complete crack system gradually with the increase of the slope deformation in space. The synthetic analysis of temporal-spatial deformation evolution is the key of accurate slope prediction. It can also be concluded that the analysis of correlation among landslide deformation evolution，external influential factors and macroscopically deformation failure evidence，is an effective method to deal with step-type deformation curve of landslide.
