The penetration angle of pick is one of the key factors in the design of tooth arrangement system of double-wheel trench cutter. Based on the continuum-discontinuum element method (CDEM)

a numerical model for picks to penetrate the rock at different angles is established

and the elastic-damage-fracture fracture process of rock mass is realized by the fracture energy constitutive model. Nine groups of impact penetration rock breaking simulations are carried out within the pick’s effective angle range of 50º to 90º. The influence of penetration angle on the rock breaking performance of pick is studied

and the influence of penetration angle on the geometric arrangement of pick is discussed. The geometric arrangement principle of the pick of the tooth arrangement system is summarized. The results show that when the penetration angle decreases from 90º to 50º

the rock mass changes from tension and tension-shear fracture to shear and tension-shear fracture

the average penetration force and crushing degree of pick increase

and the leaping invasion characteristic of pick decreases significantly. Type I picks with penetration angles of 75º−90ºand type III picks with penetration angles of less than 55º play an auxiliary role in rock breaking

while type II picks with penetration angles of 55º to 75º can produce a wide range of horizontal non-penetrating cracks in the rock mass and play a major role in the process of breaking rock mass in the tooth arrangement system. Two type II picks have successively penetrated into the rock mass between the better broken sections of the rock mass

two type II picks forming the mechanical model of the basic rock breaking unit

and several basic rock breaking units are arranged according to the sinusoidal form

thus forming a design method of tooth arrangement system. The research results provide a theoretical basis for perfecting the design method of the tooth arrangement system of the double-wheel trench cutter and breaking the technical barriers in the design method of the tooth arrangement system of the double-wheel trench cutter abroad.