The invention discloses a fixed-distance adjusting granulator for PBT production, and relates to the technical field of PBT production, the fixed-distance adjusting granulator comprises a workbench, a telescopic distance adjusting assembly and a granulating assembly, a machine frame is fixed below the workbench, an upper frame body is fixed above the workbench, an air cylinder is installed below the inner side of the upper frame body, a piston rod is arranged on the lower side of the air cylinder, and the telescopic distance adjusting assembly is connected with the piston rod. A lifting plate is fixed to the lower portion of the piston rod, and a fixing plate is installed below the lifting plate. According to the fixed-distance adjusting granulator for PBT production, the length of the granulating assembly is adjusted through the electric telescopic rod, the distance between the granulating assembly and a PBT plastic strip can be adjusted, granulating operation is conducted based on different distances and lengths, the granulating effect of different lengths can be achieved in cooperation with constant-speed feeding of the PBT plastic strip, and therefore the fixed-distance adjusting effect can be achieved; and in addition, the pelletizing operation can be carried out in the feeding process of the PBT plastic strips, a plurality of cutters do not need to be transversely arranged, fixed-distance adjustment is achieved by adjusting the distance of the cutters through frequent sliding, and the operation is relatively simple and efficient.