The invention relates to a production method of a bus duct bridge, which uses high-density polyethylene and medium-density polyethylene as a combined modified matrix, and is cross-linked and modified with a cross-linking agent under the action of an initiator, and then melt-grafted and polymerized with maleic anhydride Form a multi-grafted modified polymer, and blend and modify with surface-treated inorganic rigid particles. The inorganic rigid particles are one or more of nano-calcium oxide, glass microspheres, nano-silica, and nano-magnesium carbonate. It is extruded with processing aids through a twin-screw extruder, melted and pre-plasticized and extruded into a mold on a shaping table to be shaped, and circulating water is added to the outside of the mold to cool and shape in a vacuum, and then pulled by a tractor, cut into shape, and anti-corrosion. On the basis of static electricity, the brittleness, creep resistance, yield strength and processing performance of extruded busway bridges are improved, and the service life is longer.