This paper presents a study on the radiation corsslinking modification of high-density polyethylene (HDPE) filament by ,60,Co γ-ray. The HDPE filament netted with fibre glass is middle lamella and quality key of reinforced heat shrinkables. Our study are modifying the HDPE filaments by ,60,Co γ-ray with the four atmospheres (in air, partial air; inert gases and vacuum) at room temperature and observing their relevant propeties. The optimal irradiation condition has been obtained. That is kind of inert atmosphere. In inert atmosphere radiation crosslinking doesn't depend on the dose rate study choose, but primarily on the absorbed dose. The influences of absorbed dose and irradiation condition on the gel fraction and tensile strength have been examined. The material heat resistance and heat shrinkable ability was considerably improved with almost no change on its mechanical strength. The radiation modification filament was successfully used in reinforce heat shrinkables and can meet completely the requirements of the reinforced heat shrinkable materials.