<p>Large-diameter drilling method is a prevalent method for preventing and controlling rock burst, and the spacing between the large-diameter drilling hole and anchoring hole is a critical factor influencing the roadway stability and relief effectiveness. In this study, a mechanical model for optimal matching between the large-diameter drilling hole and anchoring hole was established following the principle of synergistic control. The influence of large-diameter drilling hole diameter on the optimal spacing under the synergistic relief effect was investigated by integrating theoretical analysis, numerical simulation, and field practice. The results suggest that the hole spacing achieved a synergistic effect in a certain range when the optimal hole spacing increased linearly with the hole diameter. For instance, when the anchoring hole diameter was 20mm, an increase in the aperture ratio from 5 to 10 brought about an increase in the optimal spacing from 0.25m to 0.45m. Additionally, the vertical stress between the large-diameter drilling hole and anchor hole increased nonlinearly under the condition of constant pore ratio but varying hole spacing. Both excessively small and excessively large hole spacings were detrimental to the pressure relief effect. In the engineering practice, optimizing the hole spacing from 0.55m to 0.45m in the No.1208 working face contributed to reducing coal body drilling cuttings and the roadway moving quantity by 33% and 28%, respectively. This demonstrates that the pressure relief-support reinforcement synergistic effect should be fully considered in optimization design.</p>