Air duct check valve

The invention relates to the technical field of check valves, in particular to an air duct check valve which comprises a valve body with an air inlet and an air outlet, a valve shaft is arranged in the valve body, a valve block is rotatably arranged on the valve shaft, and the valve block is close to one side of the air outlet and rotates towards one side of the air outlet. A valve seat for limiting rotation of one side of the air inlet of the valve plate is arranged in the valve body, a limiting piece is arranged in the valve body, and the limiting piece is located on the rotating path of the valve plate and used for preventing the valve plate from continuously rotating forwards and reducing the rotating angle of the valve plate. The turnover angle of the valve plate is limited by arranging the limiting piece, so that the valve plate is automatically closed, and high-temperature harmful gas is prevented from flowing back as much as possible when a fire occurs. 本申请涉及止回阀的技术领域，尤其是涉及一种风道止回阀，其包括包括具有进风口和出风口的阀体，所述阀