By blending low —halogen flame — retarding agent with the basic resin and using γ irradiation FR — HDPE/EPDM for cable and wire insulation with 125℃ heat resistance was prepared. The mechanical and electrical measurement showed that radiation crosslinking improves some essential properties of the material, such as the heat resisteance, tensile strength ,et al,. The dynamic flammability of the material was researched by cone calorimeter,it was found that radiation crosslinking decreases both release heat rate and effective heat of combustion while burning, besides,crosslinking increases oxygen index and the residues of combustion though the time to ignition of the irradiated material is somewhat decreased. The work was compared with the tradiational method TG measurment.