Abstract: Cyclic triaxial test of Ningbo saturated remolded clayey silt is carried out to study the effects of confining pressure, dynamic stress, drainage condition, temperature and frequency on the dynamic characteristics of soil. The relative dynamic stress is proposed to analyze the variation of cumulative plastic strain under different confining pressure and dynamic stress. Establish an empirical formula for the relationship between pore pressure and accumulated plastic strain. The results show: When the dynamic stress, related to confining pressure, reaches a certain level, the cumulative plastic strain suddenly become larger and the sample is not destroyed. The greater the relative dynamic stress, the greater the cumulative plastic strain. The empirical formula of pore pressure ~ cumulative plastic strain can be used to calculate the cumulative plastic strain of clayey silt after long-term vibration load. Finally, the decrease amplitude of cumulative plastic strain becomes more and more small with the increase of temperature under the same temperature gradient (15℃).