<p>The development of the Special-shaped Polycrystalline Diamond Compact (SPDC) cutters has significantly improved the rock-breaking efficiency of PDC bits. However, due to the complex geometric structure of the SPDC cutter, its rock-breaking mechanism is still unclear, particularly regarding mesoscale level and energy dissipation analysis. To deepen our understanding of the rock-breaking mechanisms of the SPDC cutters, this study introduces a 3D discrete element model. This study systematically assesses the rock-breaking characteristics of four types of SPDC cutters, considering crack propagation, cutting force responses, rock-breaking efficiency, and energy dissipation. The research findings indicate that compared with other cutters, the Stinger cutter promotes the shear failure of rocks, however, the rocks still mainly fail in tensile, and the cutting depth has no significant influence on the failure mode of rocks. In addition, at a larger cutting depth, the dip direction distribution of cracks produced by each cutter is more uniform. As far as the total energy consumption is concerned, the Stinger cutter stands out as the highest energy consumption, because of its highest friction energy consumption ratio among the four cutters. When the cutting depth exceeds 0.2&#xa0;mm, the comprehensive rock-breaking efficiency (rock chip parameter, <i>P</i>_C) of each cutter follows the order: the Axe-shaped cutter &gt; the Cylindrical cutter &gt; the Three-blade cutter &gt; the Stinger cutter. This study has deepened our understanding of the rock-breaking mechanism of the SPDC cutter and provided new insights for evaluating its rock-breaking efficiency.</p>