The heat transfer medium is nitrogen (inert gas), and the crosslinked polyethylene has excellent electrical properties, and the production range can reach 500KV level. Using the polyethylene insulation material containing silane crosslinking agent, the extrusion method of 1+2 is adopted to finish the extrusion of different shielding layer-insulation layer-insulation shielding layer, and then the cooled insulated wire core is immersed in hot water at 85-95℃ for hydrolytic crosslinking, because wet crosslinking will affect the moisture content in the insulation layer. Generally, the highest voltage level is only 10KV. The invention relates to an application method of functional master batch with chemical crosslinking and radiation crosslinking. At present, polyethylene cable material adopts cross-linked functional masterbatch, and a small amount of functional masterbatch is added to ordinary polyethylene cable material particles, and the extruded cable can become cross-linked cable. There are three kinds of functional masterbatch for cable crosslinking: chemical crosslinking, electron beam crosslinking and ultraviolet radiation crosslinking. The model is DH- 125Y, and the appearance is colorless LLDPE plastic particles. Wire and cable factories only need to buy LLDPE ordinary plastic particles commonly used in the market, such as LLDPE 7042. Add 1 kg DH- 125Y functional master batch into 25 kg LLDPE7042 plastic particles, turn them evenly by hand, put them directly into the extruder for laying cables and wires, and extrude cables to make cross-linked wires and cables. This functional masterbatch can produce crosslinked wires and cables of 35KV and below.