Abstract: The application of full-face tunnel boring machine (TBM) in mine mining is gradually popularized. There are some problems in the construction of tunnels with hard surrounding rocks, such as difficulty in tunneling and serious tool loss. How to realize safe tunneling of high-strength and high-abrasion strata is of great significance for guiding underground engineering construction and energy development. Therefore, this paper puts forward a technical idea of low-pressure abrasive air jet grooving to assist hob to break hard rock. Based on the comprehensive experimental platform of low-pressure abrasive air jet assisted hob rock breaking, the effects of different cutting depths on the stress and rock breaking of hob rock breaking tools are studied. The PFC is used to numerically analyze the variation laws of vertical load, crack propagation, specific energy consumption and rock stress field under different grooving depths. These can further explain the reasons for the reduction of cutter force during the rock breaking process of grooving auxiliary hob. The main conclusions are as follows: the bottom of the notch is the stress concentration area in the process of rock breaking by the hob, and the main crack extends from the position where the hob interacts with the rock to the bottom of the notch. When the notch depth is greater than 8 mm, the rock failure feature of “rock ridge” with high indentation of the hob and low bottom of the notch is formed. With the increase of the notch depth, the height of the rock ridge gradually increases. After grooving, the main crack runs through the grooving edge and rock section. It will present a triangular rock fragment, and the deeper the cutting depth, the larger the volume of the rock fragment and the smaller the maximum vertical load of the hob. The numerical simulation results are consistent with the related experimental results. When the notch of low-pressure abrasive air jet is 20 mm, the maximum vertical load of hob is 68% of that without notch. After grooving, the rock stress on both sides of the cutter is reduced during the rock breaking process of the hob, which further reduces the transmission force of the cutter during the rock breaking process of the hob and transmits it to the bottom of the grooving. The groove removes the lateral constraint and reduces the vertical load of the cutter penetration. Large rock fragments are formed to reduce the specific energy consumption of rock breaking.