The invention discloses a diameter-varying feeding device which comprises a first arc-shaped body, a second arc-shaped body and a baffle plate assembly, wherein the first arc-shaped body is slidably arranged relative to the first arc-shaped body; the baffle plate assembly is arranged between two ends of the second arc-shaped body and comprises a hinging beam which is fixedly connected at two ends of the second arc-shaped body; a first baffle plate which is arranged on one side of the hinging beam, wherein a first through hole is formed on the first baffle plate; a second baffle plate which is arranged on the other side of the hinging beam, the second baffle plate is rotatably arranged relative to the hinging beam, a second through hole is formed on the second baffle plate, and the diameter of the first through hole is greater than that of the second through hole. The device disclosed by the invention can be used for effectively controlling the speed of manually feeding materials, so that the building materials processed by the production equipment are relatively excellent in quality, thereby effectively satisfying the actual demand and function.