Abstract: By using a suction-controllable dynamic triaxial testing apparatus, a series of dynamic deformation tests are carried out on a unsaturated silt subjected to wide suctions imposed by the axial translation technique and vapor equilibrium method with saturated salt solution. The skeleton curves, dynamic elastic moduli and damping ratios are obtained over a wide suction range under almost constant net confining stress and suction. The effect of suction on dynamic deformation characteristics of unsaturated silt is studied. The test results show that at the same net confining pressure, the skeleton curves and dynamic elastic moduli increase with increasing suction, but the damping ratios decrease with increasing suction. As the hydraulic state of specimens changes from the boundary effect zone to the transition zone and then to the residual zone, the increase rates in the skeleton curves and dynamic elastic moduli decrease gradually, the decrease rate in the damping ratios is still obvious, and the decay rate of the dynamic elastic moduli with strain decreases with the increasing suction.