This study addressed the technical bottlenecks in pillarless sublevel caving method, such as severely fractured rock and high risks during slot raise excavation. An optimized blasting scheme based on differential borehole lengths for cutting blasting was proposed. Through the calculation and analysis of compensation space, it is found that whentheboreholelengthislessthan20m,adouble‑borehole"linear"layoutcanmeetthecompensationspacerequirements. However, when the borehole length exceeds 20 m, a triple‑borehole "triangular" layout is required to form an effective compensation space. ANSYS/LS-DYNA numerical simulations were conducted to model the dynamic blasting of two borehole layout schemes. The results show that the new borehole layout can create a uniform stress field, effectively break the target rock mass without leaving residual body, and precisely control the fragmentation boundary. An on‑site industrial trial was conducted using the optimized slotting borehole layout. The blasting produces uniform fragment sizes, with no over‑excavation, and sufficient free face for subsequent slotting and recovery blasting, showing good blasting effect.