Provided are a process and manufacturing die for forming a 3D nylon air-duct formed flame-retardant curved beam, the process for forming the 3D nylon air-duct formed flame-retardant curved beam comprising the following steps: step 1: manufacturing a 3D nylon air duct; step 2: selecting a flame-retardant carbon-fiber pre-impregnated material; step 3: laying up and pre-forming the prepreg; step 4: curing to form a composite material. the manufacturing die comprises: an upper die (1), a lower die (2), sliders (3), and an air-cock apparatus opening (4); the air-cock apparatus opening (4) is located on the lower die (2), and the sliders (3) comprise two blocks; the air-cock apparatus opening (4) is arranged at the air cock of the 3D nylon air duct; the lower die (2) serves as the reference for placing a product, the two sliders (3) are arranged at the left side and right side of the lower die (2), and the lower die (2) and two sliders (3) are covered by the upper die (1), securing the die so as to form the flame-retardant curved beam. The present 3D nylon air-duct integrally formed flame-retardant curved beam achieves the same flame retardant effect as a conventional curved beam formed of metal, and is simple to operate, has flexibility in its product shape, has higher strength and lighter weight, and is resistant to corrosion.