The rock is a geologic history product with a variable recast during its generation and transport, and has a complex non-linear property. The property from the microscopic view manifests mainly discontinuity and uncertainty for the rock’s structure, which is difficult to express with the traditional method and the linear analysis. The authors proposed a general damage model for brittle rock based on micromechanics analysis andconsidered the contribution of single crack on the representative volume element(RVE) of brittle rock by changing in scale (macro-micro-macro). The model can be expressed a phenomenological model anda micromechanical model obtained from different definitions of damage variables(macro variable and micro variable); through the order of different definitions(scalar, vector or tensor) of damage variable or of internal damage variable, the model can also be represented as an isotropic or an anisotropic damage model.