Abstract: Theoretical modeling and numerical simulations were carried out to analyze the fluctuation components of the infrasound excitation seismic wave field in non-horizontal seafloor topography and to elucidate the influence law of seafloor topography changes on the seismic wave field excited by underwater acoustic sources. Based on the time-domain finite element method, a waveguide acoustic field calculation model for shallow waters/seafloor is established in the cylindrical coordinate system, and the influence of three types of typical non-horizontal seafloor topography, namely, upslope seafloor, downslope seafloor and seafloor mountain, on the seismic wave field components of the seafloor is discussed with simulation examples. The results of the study show that the seismic wave fields in various types of non-horizontal seafloor topography in shallow seas can be accurately calculated using the time-domain finite element method. The submarine seismic wave field excited by the underwater sound source contains four wave systems: underwater acoustic waves, submarine interface waves, submarine longitudinal waves, and submarine transverse waves. Compared with the ideal horizontal seafloor, the uphill seafloor accelerates the attenuation of acoustic energy, and the greater the slope, the more sound waves leak to the seafloor when propagating over long distances, the greater the attenuation of acoustic energy. In contrast, the wave field changes on the downslope seabed are the opposite. The existence of seabed mountains makes some of the sound waves reflect and transmit to the bottom of the sea, and the degree of sound energy attenuation increases.