Pile clamping mechanism with hydraulic static pile driver has advantages of convenient for the design, improvement and use. The maximum transmission pile driving force of pile clamping mechanism of hydraulic static pile driver was analyzed. The static forces of pile clamping mechanism and prefabricated pile were researched and analyzed. The contact between prefabricated pile and pile clamping jaws under pile driving was investigated. It was revealed that when the force of pile clamping cylinder is small, the contact between prefabricated pile and pile clamping jaws under pile driving can be considered that between the elastic inner cylindrical surface and the axis parallel elastic outer cylindrical surface. When the force of pile clamping cylinder is large, the prefabricated pile contacted with pile clamping jaws under pile driving can be considered the hollow thick-wall cylinder subjected to uniformly distributed external pressure.