Mechanical excavation is widely used in tunnelling, mining and other aspects. As a primary rock breaking tool, the conical pick mainly undertakes the task of rock breaking. However, when conical pick was used to break medium or high strength rock, there are some problems, such as insufficient rock breaking capacity, too fast pick wear, too high peak cutting resistance and too large average cutting resistance. To measure those problems, this paper proposes to use the abrasive water jet (AWJ) which can cut rock easily to cut gridding kerf on the rock surface, so as to weaken the rock and assist the pick to break the rock. In this paper, the effects of grid geometry, pick position and kerf depth on rock breaking are studied by orthogonal experimental method. Furtherly, the crushing volume of the rock specimen and the conical pick holder stress are measured. It is found that compared with the case without abrasive jet gridding pre-cutting assistance, the crushing volume of the conical pick with abrasive jet gridding pre-cutting assistance is increased by 322.81% on average, and the average equivalent principal stress on the cutter holder is reduced by 19.83%, the maximum stress on the pick tool holder decreased by 31.65% on average. On this foundation, conical pick and AWJ gridding pre-cutting combined method can improve the rock breaking ability of conical pick.