在充分考虑岩体损伤、地层压力影响的基础上，运用损伤和断裂理论，结合预裂成缝的三个阶段：开裂、扩展和止裂，系统分析了预裂成缝的机理。研究表明，岩体的损伤和地层压力作为岩体成缝的影响因素不容忽视，预裂成缝是应力波和爆生气体综合作用的结果。 Based on the theory of damage and fracture and considering the three stages of pre-splitting, such as cracking, spreading and arresting, the mechanism of pre-splitting into fracture is systematically analyzed based on the consideration of rock mass damage and formation pressure. The results show that the damage of rock mass and formation pressure can not be neglected as the influencing factors of rock mass fracturing. The pre-cracking fractures are the result of the combination of stress wave and gas explosion.