Abstract: The dynamic triaxial tests are the most conventional laboratory method to obtain the deformation and the strength properties for soils. A series of high cycle dynamic triaxial tests are conducted on a typical silty clay, the ground soil along high-speed lines. The comparisons among dynamic strain, pore pressure and the critical dynamic stress ratio of the test samples are made to study the effects of simulation difference between the in-situ and simplified test conditions, such as dynamic loading mode, drainage condition and duration of cyclic loading. The deformation, the pore pressure, the volumetric changes and the critical dynamic stress ratio under various test conditions are presented. According to the test results, to analyze the dynamic behavior of soft clay under high-speed train loading, the dynamic test with half sinusoidal waves under drainage condition is suggested to simplify the test procedure in laboratory studies.