Abstract: In this paper, we studied the variation of the granular composition, microstructure and strength of seabed sediments under continuous wave actions and the contribution of wave-induced seabed fluidization to the physical properties of seabed sediments. The silt sediment used in the experiment was taken from the modern Yellow River delta. The experiment includes two rounds under the continuous wave actions of 5cm, 10cm, 15cm in height. Undisturbed samples and surface remould samples taken from selected areas of the soil bed were used for testing of granular composition and microstructure property variations before and after liquefaction, and the penetration strength and the evolution of liquefying failure interface were measured every 2h during the experiment. The results show that the grain size of seabed sediments within a certain depth was getting coarser with the seabed liquefaction due to the sieving away of fine-grained materials and the increase in sediment strength. The features of bed granular composition, microstructure properties and strength are closely related to the variation and the development rate of the liquefied failure interface. It is observed that the liquefaction seepage plays an important role in the reconstruction of bed and the changes in granular composition and microstructure properties, which resulted in the upward transportation of fine-grained materials at certain depths inside the seabed and coarsening of the sediment in the vicinity of liquefied boundary. The grain size sorting of seabed sediments in turn caused a substantial increase in the strength of the soil bed. Therefore, liquefaction is an important factor to the non-lunification of the composition and strength of the silty seabed.