Abstract: For the complex nonlinear impact dynamic problem of impacting coal with high pressure water jet, the coupling algorithm of smoothed particle hydrodynamics (SPH) and finite element method (FEM) was used to simulate the crushing process of coal under the impact of high pressure water jet, the law of stress and coal breakage was analyzed. According to the results, the coal is mainly damaged by the tensile and shearing. The action zone of tensile stress extends outward with the coal breakage while the shear stress mainly affects the impact axis. The process of coal breakage by impact load of water jet can be divided into two stages of crushing accumulation and rapid crushing. The crushing speed of coal shows the alternation of fast and slow.