Abstract: In order to more high efficiently mine the coal bed methane ,the particle impact drilling technology was applied to improve the drilling speed of the seam drili ng. Based on the analysis on the suitability of the particle impact drilling technology applied to the seam drilling,the coupling smooth particle hydrodynamics( SPH) and the finite element method( FEM) were applied to simulate and study the three dimensional nonlinear dynamics of the particle impact breaking in the seam and rock. Meanwhile, according to the coal and rock features ,an optimization was conducted on the particle impact drilling parameters. The variation law of the particle impact parameters with th e depth the coal and rock breaking depth were obtained. The results showed that in consideration on the particle favorable returning condition,when the drilling was conduc ted in seam,the optimum value selection scope of the particle impact parameters was optimized,thus the particle shooting velocity was 80 ~ 100 m 1 s,the particle diameter was 1.0 ~ 1.5 mm and the shooting angle was 6°~ 12°. The particle impact drilling technology could have a high efficient and practice in the mining of the coal bed methan e