It is an urgent engineering technology requirement for rigless drilling explorers to keep the supporting force of the good wall and prolong the working cycle of the drilling bit, and the reduced rock-cutting strength without rock cracking could ensure the supporting force of the good wall to drilling explorer, and also extend the life of drilling bit. The rock-cracking model with high-voltage liquid discharge is established and simulated so as to obtain the characteristics of rock-cracking. The experimental test further verifies that the presented rock-cracking model of high-voltage liquid discharge can reduce the rock-cutting strength under the condition that the good wall does not collapse.