Coal bump is a dynamic process,thus it is necessary to reveal the process validly.2D-ball code is an efficient approach developed by the authors based on the basicDEM rationale proposed by Cundall.Numerical simulations show that the coal bump experiencesa process of energy accumulation,sudden release of energy and energy decrease.The stiffness of coal particles has a great influence on the coal bump morphosisand particle velocity.Generally,the larger the stiffness of particles,the longer the shootingoff period and the larger the bump velocity.This is in agreement with the results of laboratoryexperiment and in-situ studies.However,the stiffness of particles has an influence onthe quantity value energy and no influence on the releasing energy pattern of the coalbump. Coal bump is a dynamic process, thus it is necessary to reveal the process validly. 2D-ball code is an efficient approach developed by the authors based on the basic Dem rationale proposed by Cundall. Numerical simulations show that the coal bump experiencesa process of energy accumulation , sudden release of energy and energy decrease. stiffness of coal particles has a great influence on the coal bump morphosis and particle velocity. Generally, the larger the stiffness of particles, the longer the shooting off period and the larger the bump velocity. This is in agreement with the results of laboratory experiment and in-situ studies. However, the stiffness of particles has an influence on the quantity value energy and no influence on the releasing energy pattern of the coal bump.