Abstract: Firstly,rock material under stress is divided into two parts for yielded and unyielded material.According to the differences of these two parts under stress,a damage model for rock is established on the basis of it by introducing energy theory of yielding or failure for rock.Secondly,making use of statistical damage theory,a statistical damage evolution equation that reflects the full process of rock failure has been developed.A statistical damage constitutive model of rock under a specific confining pressure has been set up.At last,the model has been modified rationally by discussing the empirical relation between parameters of the model and confining pressure of rock.A unified three-dimensional statistical damage constitutive model applying to the condition of different confining pressure has been founded.It has less parameters and is simple and easy to apply,especially,it can also reflect characteristics about the conversion between hardening and softening mutually with the changing of the confining pressure.And its rationality has been shown compared with its test.