Abstract: The mechanical properties of sand with layered structure is different from the pure sand or the mixed sand containing a certain content of fine particle． The study used the method of sand settling in water to prepare silty sand of sediment deposition in the self-made box，and investigated the law of development of dynamic pore water pressure in the saturated silty sand of sediment deposition through dynamic triaxial liquefaction test． The following conclusions were drawn from the test results: Dynamic pore water pressure could not reach the effective consolidation pressure of saturated silty sand of sediment deposition，it was only 70% ～ 80% of effective consolidation pressure，but the corresponding double amplitude axial strain could reach 0. 05; When the confining pressure was 50 kPa，its dynamic pore pressure model could be expressed by the arcsine function; When the confining pressure was 100 kPa and 200 kPa，its dynamic pore pressure model could be expressed by the hyperbolic function．