From the perspective of time domain, the propagation characteristics of sound waves in seawater can be seen more intuitively. In order to study the influence and characteristics of seamount on low frequency acoustic propagation, the research of this paper used the Finite Element Method (FEM) based on time domain to set up a full-waveguide low-frequency acoustic propagation simulation model, and discussed the influencing laws about acoustic propagation on seamount. The simulation results show that Seamounts can hinder the propagation of sound waves, weaken the energy of sound waves. The topographic changes of seamounts can cause the coupling and transformation of acoustic signals during the propagation which can stimulate the seabed interface wave.