According to a locking device for bridge structure shock absorption control, three fan-blade-shaped piston pieces are overlapped to form a piston of the device, rubber pieces are adhered to the outer layers of the three fan-blade-shaped piston pieces, the piston is fixed to a pull rod, the piston and the pull rod are arranged in an oil cylinder filled with silicone oil, the oil cylinder is thereby divided into three portions through the left piston piece and the right piston piece, and the pull rod drives the piston to conduct longitudinal displacement and torsional displacement. The viscous force produced when the silicone oil passes through orifices controls the movement of the pull rod, the left piston piece and the right piston piece are simultaneously locked, and the locking strength of the device is enhanced. Meanwhile, hole diameter automatic adjusting systems are arranged inside the left piston piece and the right piston piece respectively, and each hole diameter automatic adjusting system is composed of a drainage hole, one of the orifices, two springs and a trapezoid steel block, and the longitudinal locking speed of the device is improved through the pressure intensity difference caused by the difference of the flow velocities of liquid on two sides of the trapezoid steel block when the piston moves. Furthermore, the fan-blade-shaped piston pieces of the device stir the silicone oil to flow when torsional displacement occurs, and the force exerted by an earthquake on a bridge structure is reduced through energy produced by the earthquake in the viscosity dissipation portion of the locking device.