In this study, the undrained behaviour of silt under low stress level is studied. An effective preparation methodfor built in silt samples in the triaxial test was firstly developed. By triaxial testing of samples at low confining pressures itwas found that silt easily loses stability and liquefies. Loose silt may show temporary liquefaction under static loading, anddevelop full liquefaction under cyclic loading. The most important factors influencing the silt behaviour are porosity, confin-ing pressure, consolidation state, cyclic loading level and number of cycles. The maximum obtainable shear stress is primarilya function of the confining pressure and the internal frictional angle. The actual structure of the silt material is the key factorin controlling its behaviour.