The invention discloses a flexible flap valve device capable of controlling and guiding through tidal estuary hydrodynamic force. The flexible flap valve device comprises a composite geomembrane, a weight-adjustable lead hammer, bidirectional plastic geogrid meshes and a plurality steel sheet piles; the steel sheet piles are arranged at intervals evenly, the bidirectional plastic geogrid mesh is arranged between each two steel sheet piles, the composite geomembrane is covred on one side of each bidirectional plastic geogrid mesh, and the upper end of the composite geomembrane is fixed on the bidirectional plastic geogrid meshes; and the lower end of the composite geomembrane is suspended with the weight-adjustable lead hammer, the composite geomembrane is in a drooping state in the water,under the action of tidal dynamics, the water flow passes through the bidirectional plastic geogrid meshes, the lower part of the composite geomembrane is lifted under the pushing function of the water flow, and the water flow flows through a flexible flap valve from a gap between the composite geomembrane and a riverbed. By means of the flexible flap valve device capable of controlling and guiding through tidal dynamic force and tidal estuary hydrodynamic force, the water flow control on the water passing section can be naturally completed, and the construction and operation costs are greatlyreduced.