In the small plain river with almost zero head, the traditional water pumps are faced with a series of problems，such as low efficiency, poor stability and high erection cost. In order to improve the hydrodynamic conditions of small plain rivers, an innovative method of using flapping hydrofoil to promote the flow of water in small rivers was proposed. Based upon this, the calculation model of flapping hydrofoil was established, and the effects of different flapping frequencies and different incoming flow velocities on the hydrodynamic performance of flapping hydrofoil were numerically simulated. A test bench for the hydrodynamic performance of flapping hydrofoil was designed and verified in the circulating channel. The results showed that the flow of flapping hydrofoil device was directly proportional to its flutter frequency, and the head was directly proportional to the square of frequency. At a fixed frequency, the tail vortex of flapping hydrofoil gradually formed a double row anti-Karmen vortex street from the chaotic state with the increase of velocity, and the pumping efficiency of the device gradually increased to the optimal efficiency point. The flow velocity continued to increase, the anti-Karmen vortex street changed to a single row, and the efficiency decreased rapidly. In addition, the flapping hydrofoil device had the advantages of low head and large flow, and had unique advantages in pushing water in plain rivers.