The present invention discloses a weatherability-modified polyethylene cable sheathing material, the weatherability-modified polyethylene cable sheathing material comprises 8 to 12 parts by weight of chlorinated polyethylene, 18 to 21 parts by weight of an ethylene-octene copolymer elastomer, 25 to 30 parts by weight of modified calcined clay, 5 to 7 parts by weight of 800 # paraffinic base rubber oil, 0.5 to 0.8 part by weight of active magnesium oxide, 4 to 5 parts by weight of superfine talc powder, 1 to 1.5 parts by weight of active zinc oxide, 0.45 to 0.55 part by weight of an environmental protection stabilizer, 1.5 to 2 parts by weight of microcrystalline wax, 0.7 to 0.8 part by weight of titanium dioxide, 0.5 to 0.8 part by weight of 4,4 'bis (alpha, alpha-dimethylbenzyl) diphenylamine, 1.5 parts by weight of dicumyl peroxide and 1.2 to 1.3 parts by weight of triallyl cyanurate, the mass fraction of octene monomers in the ethylene-octene copolymer elastomer exceeds 20%. The weatherability-modified polyethylene cable sheathing material is conductive to uniform addition of inorganic powder, is wide in range of technology, greatly accelerates the curing speed, increases the crosslink density, and improves the heat resistance and weatherability of mixed rubber.