The sandwich foam materials of wind turbine blades are mainly polyvinyl chloride (PVC) and styrene–acrylonitrile (SAN) foams due to their good mechanical properties. However, PVC foam is unrecyclable and not resistant to high‐temperature conditions, while SAN foam is more expensive than PVC foam. Polyethylene terephthalate (PET) has irreplaceable advantages than both PVC and SAN foams because of its better mechanical performance, fantastic heat‐resistant, low cost, and environmental friendliness (100% recyclability). In this article, the mechanical properties, thermal stability, resin uptake, and cellular morphology of PET T92, PVC H60, and SAN T400 foams were discussed. The results showed that the mechanical properties of T92 were equivalent to the existing H60 and T400, and even exceed their properties. It was found that the thermal stability of T92 was better than H60 and T400 under the same high temperature. Moreover, the pore of T92 was more uniform and regular than H60 and T400. Furthermore, the overall cost of T92 was lower than H60 and T400. The findings suggest that PET foam with a density of 100 kg/m3 can completely replace PVC 60 kg/m3 and SAN 71 kg/m3 foams from the perspective of mechanical performance, cost, thermal stability, and environmental protection.