The micro unit inside the rocks was investigated for the characteristics of stress distribution of the micro unit under macro stress effect and the stress distribution of the micro unit was considered as a normal distribution.  Based on this, a constitutive mode of rock damage was built by considering all kinds of variations and the resolution of the parameters was derived. The results showed that the mode could be well suited to explain all the rock damage modes under different conditions, the intensity of ambient pressure on the peak value as well as the impact laws of the residual strength.