Abstract: The modulus, dampings and properties of liquefaction are tested for three kinds of coal ash. It is indicated that the stress-strain relationship under the excitation of vertical and torsional vibration can be characterized with a hyperbola curve. The values of the dynamic shear modulus and the damping factor are close to those of sandy soil. The shear strain level and confined pressure are the two principal factors affecting the damping value. The influence of the density on the damping of fine coal ash is much less. The damping value is more less independent of the water content. The antiliquefaction strength of fine coal ashes with low density is quite low, and the effect of consolidation ratio is also not important.