<p>The decomposition of large workpieces is increasingly required in various fields. Traditional methods, such as mechanical sawing and diamond wire saw cutting, generate large cutting forces and rapid tool wear, encountering challenges in effectively cutting large-thickness structures. Blasting erosion arc machining (BEAM), with adaptable machining equipment and high energy density, offers a promising alternative. In this study, BEAM is applied to the cutting of large-thickness workpieces, and the mechanism of arc breaking in BEAS is analyzed. An experimental system is developed to realize high-speed fluid flow and mechanical motion through the disk electrode rotation. Besides, a fluid flow simulation model is established to explore the compound arc-breaking effects of hydrodynamic forces and mechanical motion. Experimental results under varying rotation speeds, pulse duration times, and cutting depths verify that BEAS can achieve higher cutting speeds, lower tool wear ratio (TWR), and narrower kerf widths. The proposed BEAS method shows strong potential for applications in nuclear facility decomposition, oil pipeline maintenance, and underwater rescue operations.</p>