The utility model relates to a hydraulic flap gate, which is composed of a left half gate body, a right half gate body, a separation and pressing device composed of oil cylinders and a piston connecting rod. Three oil cylinders are all distributed and fixed on the left side of the left half gate body. The right end of the piston rod of an oil cylinder is connected with the right half gate body. Two sealing rings are arranged at end surface between the left half gate body and the right half gate body. A gate plate is arranged between the two sealing rings. The rotary centre hole of the gate plate is sheathed on the piston rod. The rotation of the gate plate realizes the opening and closing of a pipeline. The three oil cylinders directly push and pull two half gate bodies under the action of hydraulic oil, which makes the pipeline deformed and realizes the separating and closing of a sealing surface. The connection of the separation and pressing device and the two half gate bodies has the advantages of two combination into one, simple structure and compact structure. The utility model is suitable for the use of various low pressure gas pipelines.