Abstract: Reflection and transmission of inclined incident plane-wave from seawater to a stratified fluid-saturated porous medium ocean bottom including unconsolidated sediments is studied based on the typical ocean bottom medium.The dispersion of sound velocity and attenuation of longitudinal and transverse wave in unconsolidated sediments and fluid-saturated porous medium basement are analyzed.Attention is focused on the effect of frequency-thickness products variation on the reflection coefficient of displacement potential.The results show that for a certain sediments thickness,the sound field in seawater is influenced significantly by sediments at relatively higher frequency and by basement at relatively lower frequency.In addition,the curve of reflection coefficients of displacement potential with different frequency-thickness products show that there are a series of formants with angle of grazing,and the number of formants decreases as angle of grazing decreasing.