Abstract: In order to study the occurrence mechanism of coal and rock dynamic disasters, uniaxial compression experimental and confining pressure loading experimental were carried out on 3 kinds of concrete samples with different strength, and the failure process of specimens under confining pressure was monitored by acoustic emission instrument; the damage characteristics of specimens were observed at the microscopic level by numerical simulation. The experimental results show that the failure type of the specimen under confining pressure is single and tensile fracture occurs near the middle of the specimen. The simulation results show that under the action of longitudinal tensile stress, the initial failure of the sample starts from the interior of the rock and gradually expands along the transverse direction to both sides; when the confining pressure makes the longitudinal tension reach the tensile strength of the rock mass, the initial failure zone is enlarged with the increase of confining pressure, until the instantaneous fracture occurs.