An omega-shaped bidirectional low-lift water pumping device comprises a bidirectional water inlet and outlet channel, a rapid gate, a bidirectional low-hump siphoning type water outlet structure, a vacuum breaking device and a pump device. The pump device is perpendicularly arranged in the center of the water inlet and outlet channel. The portions, at the two sides of the pump device, of the water inlet and outlet channel are respectively provided with a direction-adjusting gate port. A horizontal separating board is arranged on the upper middle portion of the water inlet and outlet channel. The portions, at the two sides of the pump device, of the horizontal separating board are respectively provided with a diving hole provided with a buoyancy tank direction-adjusting gate. The buoyancy tank direction-adjusting gates are shared by the diving holes and the direction-adjusting gate ports. The buoyancy tank direction-adjusting gates are controlled to change the direction of water flow, so that bidirectional water pumping is achieved; a top vent hole port of the low-hump siphoning type water outlet structure is connected with a vacuum break valve. The omega-shaped bidirectional low-lift water pumping device satisfies the requirement for an efficient water pumping device of a bidirectional low-lift pump station and solves the technical problems that due to the fact that the axial size of a vertical pump device is large, the water outlet level of the vertical pump device is higher than the water level of an outlet of the pump station and lift is wasted.