The invention discloses a noise reducing device for a large-thickness blunt trailing-edge airfoil. The noise reducing device comprises a blunt trailing-edge body and a zigzag trailing-edge body, wherein the blunt trailing-edge body and the zigzag trailing-edge body are connected; the zigzag trailing-edge body comprises an upper zigzag part and a lower zigzag part; the upper zigzag part is connected with a fixed plate body; the fixed plate body is connected with the lower zigzag part; and the fixed plate body is fixed on a trailing-edge plane of the blunt trailing-edge body. According to the noise reducing device disclosed by the invention, the zigzag trailing-edge body is fixed on the trailing-edge plane of the blunt trailing-edge body, so that aerodynamics characteristics of the large-thickness blunt trailing-edge airfoil can be improved, and vortex of the airfoil is effectively stopped and segmented when the turbulence intensity of incoming flow is relatively-high; in addition, aerodynamic noises of the large-thickness blunt trailing-edge airfoil can be greatly reduced, and utilization rate of wind energy of blades and the operation stability of a wind turbine are improved. The noise reducing device disclosed by the invention has the advantages of simple structural design, and easiness for mounting, popularization and application.