Abstract: It is necessary to clarify the physical and mechanical properties of seabed sediments before designing offshore engineering structures. Basic physical property tests were carried out on surface sediments collected from the Pearl River Estuary in the northern South China Sea and from Wenzhou Port to the central East China Sea. Parameters related to natural water content, specific gravity,Atterberg limits, and particle size distribution were obtained. In addition, one-dimensional compression tests,K₀ consolidation tests, and permeability tests were conducted to investigate the consolidation and permeability characteristics of the sediments. Finally, scanning electron microscopy tests were performed to analyze the microstructure of the surface sediments. Experimental results show that the sediments in both sea areas are low-liquid-limit clays. The sediments in the East China Sea are mainly composed of fine-grained soil(particle size <0.075 mm), and their basic physical and mechanical properties are relatively uniform. In contrast, for the sediments in the South China Sea, the parameters characterizing physical and mechanical properties exhibit a clear variation with spatial distribution. The liquid limit, clay content, and compression coefficient increase with increasing distance from the coast, while the consolidation coefficient decreases with increasing offshore distance.