A recycled PET foam material and a manufacturing method thereof are characterized in that a recycled material can be used. The manufacturing method includes the following steps: uniformly mixing PET resin, chain extender, antioxidant, flame retardant and heat stabilizer, and then mixing with a twin-screw extruder to obtain a foam PET resin. The PET foaming material obtained is a material having the advantages of light weight, large rigidity, high specific strength, good electrical insulation, good sound insulation and the like, low raw material cost, simple manufacturing process and environmental protection.