There exist a lot of deep rock mechanics engineering in mining and tunnel excavation. Due to the factors or natural factors, such as the excavation of the deep rock mass stress state of equilibrium, the deep rock mass elastic strain energy release, the original micro cracks expand, make the adjacent cracks in the rock mass, affect the mining safety. And, in the many factors influencing the mine safety production, water is the most active factor. When the deep rock mass micro crack propagation through, the original crack in the high hydrodynamic pressure will be transformed into a great hydrodynamic pressure, at the same time the hydrodynamic pressure will lead to further expansion of rock cracks and adjacent cracks between the through, and ultimately lead to the destruction and instability of rock mass. Therefore, the dynamic water pressure acting on the fractured rock mass is a practical problem facing the mining of metal and nonmetal minerals, especially in the deep mining area. In this project, the crack initiation, propagation, coalescence and interaction of rock, rock mass structure weakening and multi fracture rock mass fracture process are studied.