Abstract: The characteristic of large deformation damage and the existing analysis method in rock slope engineering was considered; meanwhile， based on the structural information collection of the rock slope， a numerical space model of rock slope was established through GeoSMA-3D which was developed by the first author’s team. The numerical model can represent 3D model of rock slope， using the numerical manifold method (NMM) to simulate the process of large deformation in rock slope， based on the block theory and the gravity-increase method which is often used in the finite element method， through increasing the gravity of rock mass continuously， until the “key blocks”begin to slide， and the slope generates large deformation failure. At the same time， the safety factor of slope can be confirmed if the displacement of the most dangerous “key block” increases sharply with the increase of gravity. At last， an example of slope engineering in Liaoning is presented to achieve the characterization of large deformation damage in rock slope， proposing solutions for the slope support， providing a reference for engineering construction and prevention of slope disaster.

Key words: gravity increase method, blocky rock mass, large deformation analysis, NMM(numerical manifold method), rock slope