The invention provides a duplex rack horizontal clamp and coupling switch self-adaptive robot finger device and belongs to the technical field of robot hands. The duplex rack horizontal clamp and coupling switch self-adaptive robot finger device comprises a base, two finger sections, two joint shafts, a motor, a semi-gear, a gear, a connector, a rotating shaft, a lower rack, an upper rack, an intermediate shaft, two limiting blocks, a sleeve, a spring piece and the like. The duplex rack horizontal clamp and coupling switch self-adaptive robot finger device achieves multiple grabbing modes, including horizontal clamping grabbing, coupling grabbing and self-adaptive grabbing, of a robot finger. Stable switching between horizontal clamping and coupling is achieved through the semi-gear. Besides, due to the arrangement of the semi-gear, the transmission precision of the horizontal clamping stage and the coupling stage is improved, the mechanism is simplified through the self-adaptive function of a gear and rack mechanism, the contradict between the horizontal clamping state or the coupling state and the self-adaptive state is avoided through cooperation between the spring piece and the limiting sliding blocks, the grabbing range is wide, one motor is used for driving two joints, and a complicated sensing and control system is not needed; and the duplex rack horizontal clamp and coupling switch self-adaptive robot finger device is simple in structure, small in size and low in cost.