In this paper, the influence of recycled polyethylene terephthalate powder (R-PET) on fatigue life, thermal properties and micro-fracture surfaces of halloysite nanotubes (HNTs) and silica filled natural rubber composites have been studied. The total amount of hybrid filler in each formulation was kept constant at 20 parts per hundred rubber (phr). The final properties of HNTs/R-PET and Silica/R-PET compounds are considered separately and comparatively. Results indicated that the fatigue life of the natural rubber composites decreased with the replacement of these two fillers by R-PET powder. This observation might be due to the R-PET itself, which reduces the interfacial adhesion and wettability between rubber matrix and fillers. By replacing of HNTs and silica with R-PET powder, the thermal degradation of natural rubber composites was shifted to a lower temperature and the char residues was decreased, in which HNTs/R-PET composites expressed the higher temperature and char residues than silica/R-PET composites. This findings may be due to the HNTs/R-PET has less volatile matter than silica/R-PET that might enhance the degradation temperature of the natural rubber composites. SEM micrographs also exhibited weak interfacial adhesion when these two fillers were replaced with R-PET powder in NR composites.