Composites from ethylene propylene diene monomer (EPDM) rubber filled with different concentrations 20, 40, and 60 parts per hundred rubber (phr) of aluminum oxide (Al2O3) were prepared. The samples were vulcanized by gamma irradiation at doses (50,100, 150, and 200) kGy. The effects of irradiation doses and Al2O3 contents on the mechanical prorerties (particularly tensile strength, elongation at break % and hardness), physical properties (volume fraction and crosslinking density), thermal properties was studied by thermogravimetric analysis (TGA) and fire resistance was tested using Limiting Oxygen Index (LOI) and rate of burning methods of EPDM and its composites were studied. The results indicated that the improvement of mechanical as well as, physical properties occurred by increasing the concentration of Al2O3 (except the tensile strength values, where the highest values were obtained at concentration 20 phr Al2O3 in the composite irradiated at 100 kGy). The thermal stability and fire retardancy properties of the prepared composites were improved by increasing Al2O3 concentration. Generally, the addition of Al2O3 and gamma irradiation has improved composite's performance. This is suitable for preparing products of rubber serving in dynamic conditions, with longer expected service life