Abstract: Most existing literatures on low-frequency underwater acoustic propagation in shallow water focus on the acoustic propagation features in the water column,while studies on acoustic propagation features in the sediment layer or the semi-infinite basement are rarely.In this paper,based on the wave equation,a computational model for acoustic energy flux in the sediment layer and the basement as well as in the water column is built under cylindrical coordinates.On this basis,the effects of various sediment acoustic parameters on the acoustic energy distribution and the corresponding mechanisms are elaborated through numerical examples and acoustic theory.The simulation results reveal that,in the situation of sediment P-wave speed ＞ water sound speed ＞ sediment S-wave speed,the greater the values of density and P-wave speed in sediment,the more likely the acoustic energy remains in the water column without leaking to the ocean bottom,while the influence of the variation of S-wave speed is in the opposite way.Basement influence on the acoustic propagation in fluid layer is approximately negligible after the sedimentary layer is thickened to a certain degree.