Multiscale computational framework is proposed to describe progressive failure of geological body. Calculation condition and determination method of physical parameters in multiscale are established. Engineering geological model is divided into three computational scales, which include size of actual model from hundreds to thousands meters, size of mathematical mesh with meter scale and characteristic size of fracture corresponding to experimental sample scale. Strength parameters from lab can be used to describe failure in this multiscale computational framework. A new strength criterion based on distribution of shear strain strength on shear plane is introduced, in which strain is used as the strength index and shear strain strength complies with a certain distribution law. Area where shear strain is below the shear strain strength keeps linear elastic, while the rest turns into Coulomb's friction. Nonlinear behavior of material such as yielding and strain softening can be described. Elasto-brittle model, strain softening model and ideal elasto-plastic model can be naturally obtained through the variation of the interval of upper limit and lower limit of strain strength. Numerical result of discrete element method shows that it is reasonable to describe the internal microscopic damage with elastic microplane and fracture microplane which are expressed with linear elastic and Coulomb's friction parameters, respectively.