In this study, the prediction model proposed by Sassa et al. (Geotechnique 2001; 51(10):847-857) for the wave-induced progressive liquefaction in marine sediment, based on two-layered inviscid fluid system, is re-examined. An alternative approach with a similar framework of Sassa et al. (Geotechnique 2001; 51(10):847-857) is developed to correct the inappropriate mechanism of wave components used. Then, a two-layered wave model which includes viscous effects is established and applied to describe the progressive nature of wave-induced liquefaction. A comprehensive comparison shows that Sassa's model overestimates the maximum liquefaction depth. It is found that the viscosity of liquefied soil cannot be ignored and the solution for an infinite seabed is not suitable for liquefaction analysis of shallow seabed. A parametric study demonstrates the significant influence of numerous wave and soil characteristics on the liquefaction depth.