Abstract: A special kind of bay facies organic sand is distributed in the coastal areas of Hainan Province. In order to study its dynamic characteristics, the tests on dynamic deformation and strength properties under different confining pressures and moisture contents are performed. The dynamic stress-dynamic strain relation, dynamic elastic modulus, damping ratio and dynamic strength of the samples under various moisture contents and confining pressures are analyzed. The tests indicate that, under the constant dynamic strain, the dynamic stress decreases with the increase of the moisture content and increases with the increase of the confining pressure. When the moisture content changes, the change trend of the dynamic elastic modulus is relatively gentle. The damping ratio increases with the dynamic strain and decreases with the moisture content. When the confining pressure changes, the damping ratio does not change obviously. It may provide a reference basis for the selection of dynamic parameters of structures in the bay facies organic sand-impregnated sand areas of Hainan Province.