Abstract: Sand liquefaction and water drainage will occur at a saturated sandy soil site under earthquakes. Similar phenomena will also happen during pile driving. However, the drainage can not be calculated so far. Based on the solutions to the Green’s functions of the solid and fluid phases in frequency domain pertaining to the Biot's governing differential equations of a two-phase saturated medium, the Sommerfeld's integral and the transformation of axisymmetrical coordinate, dynamic equations and Lamb’s integral are combined to calculate the forces acting on a single pile driven under drainage. According to the Darcy’s law, the corresponding parameters such as dynamic stiffness of a cylinder pile, pore pressure and flux in the saturated soil are calculated when the pile top is subjected to concentrated forces. The effects of some parameters such as pile slenderness on the dynamic properties of piles are revealed. The results may benefit further researches on the dynamic response of piles in saturated soil and the dynamic properties of pile-soil interaction.