Abstract: In order to study the cutting force,crack formation and debris separation process of the pick in the process of rock breaking,and further improve the efficiency of roadway excavation,the three-dimensional model of rock cutting by pick is established by SolidWorks software,and the three-dimensional finite element model of rock breaking by pick based on penetration failure and compression damage under different cutting angles and Cutting thicknesss is established by using dynamic simulation software ANSYS / LS-DYNA,the Holmquist Johnson cook(HJC) constitutive model is used to simulate rock material,and the infinite size of rock block is simulated by adding non reflective boundary conditions. The cutting force,the fluctuation law of cutting force,crack propagation and debris separation under the cutting speed of 3 m/s,the Cutting thickness of 10,15 and 20 mm,and the cutting angles of 35°,40°,45°,50°,55° and 60° are studied. The relationship between the size of rock block and the cutting force is analyzed. The results show that：using ANSYS / LS-DYNA(3D),using the method of penetration failure and compression damage,good results can be obtained for simulating the crack propagation and debris separation in the process of rock breaking;the maximum peak cutting force and the mean value of cutting force are different when the pick cuts rock at different cutting angles and depths,and the generation,propagation and fragment size of cracks are also different;with the increase of cutting angle,the number of rock blocks produced by crushing increases first and then decreases,and the cutting〖LM〗force of pick decreases at first and then increases. When the cutting angle is 50°,the number of rock blocks is the most,the cutting force is the smallest,and the cutting force fluctuation is the smallest. In order to improve the rock breaking efficiency,reduce the wear of the pick and then increase the pick life,the cutting angle of 50 ° is appropriate;with the increase of Cutting thickness,the number of blocks also increases. The research results provide a theoretical basis for improving the rock breaking efficiency,the life of the pick and the selection of cutting angle and Cutting thickness.