A bidirectional hydraulic system for operating table is disclosed, which has a switch valve connecting a bidirectional hydraulic pumping device with movable units of an operating table. The switch valve is driven by a motor, and has a valve block defining at least three outbound valve positions on the valve block's top surface, which is parallel to the inside bottom of the base, which the valve block is attached to, and thereof for controlling oil inlet and oil outlet. The switch valve switches among the outbound valve positions for respectively forming oil passages between the bidirectional hydraulic pumping device and hydraulic cylinders of the movable units.