Abstract: To achieve real-time identification of geological anomalies ahead of the excavation face, this study investigates the seismic-while-excavating (SWE) signal mechanism and propagation law, addressing the limitations of conventional pre-exploration methods such as long operation cycles and low resolution. A mechanical model of the roadheader cutting head was established to analyze the generation of P-, SV-, and SH-waves under axial thrust and shear forces. A 3-D geological–geophysical model containing the roadway, coal seam, and fault fracture zone was constructed. The 3-D elastic wave finite-difference method was used to simulate wave propagation and energy distribution. Simulations show that P-waves dominate with concentrated energy and fast velocity, while S-waves exhibit reflection and mode conversion at low-velocity layers and faults. Guided and channel waves appear in the roadway and coal seam, and the dominant frequency band of SWE signals is 50 ~ 450 Hz with a peak near 200 Hz. The study reveals the generation mechanism and radiation characteristics of the SWE source and clarifies its propagation behavior in complex media, providing theoretical support for SWE signal recognition and geological imaging.