<p>Ground vibration induced by rock blasting is a critical challenge in engineering. Controlling seismic energy that quantifies the overall vibration intensity is essential for ensuring safety and efficiency. In this study, a seismic energy calculation model constrained by the fracture boundary was proposed, establishing a unified interface to characterize the seismic energy radiation. Using a combined approach of theoretical analysis, field experiments, and numerical simulations, the control mechanisms of three key parameters were elucidated. The results indicate that the decoupling coefficient operates via a load-control mechanism. By creating a cushioning effect, it modulates the source input function and decreases the energy conversion efficiency, thereby reducing the proportion of radiated seismic energy. The free surface functions through a propagation-control mechanism. It imposes a geometric truncation on the fracture boundary, effectively blocking radiation paths in specific directions. Furthermore, the initiation position controls seismic energy through a direction-control mechanism that actively modifies the seismic energy distribution. It dominates the wavefield directionality and enables energy to be redirected away from sensitive areas through wave superposition. On the basis of these findings, practical guidelines are proposed, including an optimal decoupling coefficient range of 1.28–1.67 and strategies for optimizing free surface orientation and initiation methods. These insights provide a scientific basis for balancing vibration control and excavation efficiency.</p>