Abstract: Based on the characteristics that the failure of micro unit of rock accorded with normal distribution, this paper developed a statistical damage constitutive model reflecting the full process of rock failure by using the stress strain curve of rock and the parameter that can rationally describe the micro unit strength of rock. Hereby, the statistical damage variable of rock was modified reasonable and then the three dimensional statistical damage constitutive model reflecting the full process of rock failure was established.It is shown that the rock strength was affected by the stress state and the model was reasonable with its calculated values approximate to the test results.