To provide material basis for the further study of consolidation mechanism of marine sediment in the tidal zone of Zhoushan, the particle composition of marine sediments is analyzed by laser particle size analyzer, the chemical elements, compound species and their relative contents of marine sediments are tested, and the mineral composition of marine sediments was also analyzed using X ray diffraction techniques. The results indicate that the marine sediment is mainly composed of low liquid limit silty clay, which is high in water content rate, large in initial pore ratio and flow plastic in property. The activity index of the sediment is 12.4, indicating that it belongs to an active clay. The minerals in the sediment have a good hydrophilicity. The total salt content of the sediment is as high as 9~11.2 g/kg. The cation exchange capacity of the sediment is not strong and the organic matter content of the sediment is high (5.82~12.7 g/kg). The pH of the sediment is 7.35~8.36, showing weakly alkaline in property. The pore water of the sediment contains K⁺, Na⁺, Ca²⁺ and Mg²⁺, which makes kaolinite unstable and tend to transform into illite, montmorillonite or chlorite.