The dynamic properties of west coast marine silty sand are investigated between 1%~ 4% cyclic double amplitude shear strain using cyclic direct simple shear test apparatus. The dynamic properties are expressed in terms of secant shear modulus (Gs) and damping ratio (D). This study systematically investigates the effect of relative density, cyclic double amplitude shear strain, cyclic stress ratio, frequency, vertical effective stress and number of loading cycles on the dynamic properties of soil samples. All the tests are performed with frequency of 0.1 Hz with different relative densities 65 % and 70 %. Shear modulus decreases with increase in number of loading cycles and damping ratio increases. Shear modulus decreases with increase in cyclic double amplitude shear strain (1~4%) and damping ratio increases. Published version