Abstract: In order to study the characteristics of coal-rock damage evolution under different loading conditions, biaxial compression tests were virtually simulated by particle flow code （ＰＦＣ）. The bonded particle model was established, and the contact relationship was set. Then, the numerical simulation of the variable rate biaxial compression under different confining pressure was carried out by using the servo loading mechanism. The effect of confining pressure and loading velocity on the damage characteristics of the specimen was analyzed by studying the characteristics of some coal-rock simulation specimens about the damage morphology, micro cracks development process, stress-strain curve and acoustic emission events. The results show that: with the increase of confining pressure, the peak of axial stress of the specimen is becoming greater, and loading velocity has little effect on the peak of axial stress, there are three main stages during the micro crack development, including stable development stage, rapid increase stage and stable development stage, and the higher the damage degree of coal and rock mass, the more total number of AE events.