The study of rock whose the damage characteristic is carried out on the basis of the theory of continuum damage mechanics and rock infinitesimal strength obeys Weibull distribution function. The conventional triaxial numerical experiment under different deformation parameters (E,μ) and strength parameters (c,φ) and confining pressure which is respectively 3/6/10 MPa are carried out for the rock by using FLAC3D finite different numerical simulation software. The results of numerical experiment show that:①In the initial stage of loading, the rock shows negative damage(compaction reinforcement effect). With the increase of the axial stress, the cutting modulus decreases and Poisson′s ratio increases. ②The higher the cohesion or internal friction angle or confining pressure is, the higher the compressive strength of rock is, and the longer the plastic deformation stage is during rock deformation. ③The axial strain corresponding to the starting point of damage does not change with the change of the intensity parameters (c,φ), but decreases with the increase of the calculated initial elastic modulus and increases with the increase of confining pressure.④Poisson’s ratio has little influence on the mechanical properties and damage characteristics of rocks, and is negligible.