Abstract: Cut blasting is a commonly used method of shaft excavation blasting project. The application of bundle-hole cut blasting can improve the cut efficiency. However, the process of bundle-hole cut blasting involves the continuous and discontinuous process of the structure under dynamic load, the numerical calculation process is complex. How to quickly estimate the blasting effect of a specific cutting design has always been a key point in scientific research and engineering field. In this paper, based on the explosion stress wave superposition method, a fast calculation formula of crater radius is proposed. Meanwhile, based on continuous discontinuous element method (CDEM), the rock breaking mechanism of bundle-hole cut blasting is discussed and verified with experiments. By comparing with the experimental results, the availability of the calculation formula is verified and the rock breaking mechanism of bundle-hole cut blasting is revealed. The obtained results show that when the cut hole spacing is 4~5 times of the diameter of the hole, the blasting effect is the best. The results of this paper can provide some guidance for the design of bundle-hole cut blasting.