Abstract: Based on the analysis of rock breaking under high-pressure water jet, a rock damage mode and a damage coupling model suitable for two different stages of rock breaking progress are established with continuum damage mechanics and micro damage mechanics. The evolvement of rock damage and breakage are simulated with nonlinear FEM and the rock damage model. Numerical results agree with experimental results, indicating that the rock damage model established in this paper can simulate the rock breaking process under high pressure water jet.