Based on the stress and displacement measures of rock materials with different degree of damage during deformation under plane strain condition,this paper analyzes the characteristics of rock samples’ axial stress-displacement curves,axial-lateral displacements comparing curves and their bifurcation,network in shear zones and their changes with degree of damage.It is shown that the deformation of transient lateral compression begun at the begin of loading when there was confining pressure,then the deformation of lateral swell occurred;along with the development of axial strain,the damage occurred after the peak strength of sample;along with the development of axial strain,the degree of damage increased,rock samples’ residual strength and axial displacement decreased,the axial displacement at the bifurcation points of curves and shear zone came into being tended to further decreased,the instability of the samples was occurred easily;the networks in the shear zones begun at II phase of elastic deformation,developed in soften phase,and came into being the phase of residual strength.