Identification of adverse geological bodies in front of the tunnel excavation face is essential to take precautionary measures for safer tunnel construction. Nowadays, the interpretation of seismic data in tunnels relies more on experience, which is caused by the lack of understanding of the propagation mechanism of seismic waves in tunnels. Therefore, based on the finite element method of seismic wave in two-phase medium, we investigate the time-domain evolution characteristics of seismic wave in tunnel space with two typical adverse geologic bodies, namely, water-bearing fracture zones and lithological interfaces. The results show that under the combined influence of solid-solid and solid-fluid phase reflections, the propagation complexity of the seismic wave is significantly increased, and the obvious diffraction phenomenon caused by tunnel face plays a promoting role. The amplitude attenuation of the waves obtained from the self-defined factor is exponentially related to the propagation time, which is influenced by the energy difference of the wave itself and the degree of wave crosstalk in the propagation process. This study can provide theoretical guidance for the technological development and field application of tunnel geological detection.