Abstract: The equipment for producing fiberglass pipes mainly includes large-sized molds.The number of forming molds required for the production of fiberglass pipes (tubes) is increasing.Simultaneously, there have also been cases of shaft head failure in the production process of forming molds.In response to the cracking of the front axle head during the rotation of the forming mold required for the production of a certain fiberglass tube (cylinder), mechanical analysis and fracture observation were conducted to determine the reasons for the cracking of the front axle head: the design wall thickness of the axle head structure was too small, and the unreasonable welding process and poor welding quality caused the cracking of the front axle head.The obtained results can provide reference for the design and welding of the shaft head.