The invention discloses a low-water-absorbing cable material for a high-speed railway motor train unit and a preparation method of the Low-water-adsorbing cable material. The low-water-absorbing cable material for the high-speed railway motor train unit comprises the following raw materials in parts by weight: 81 to 92 parts of polypropylene, 43 to 55 parts of polybutylene terephthalate, 27 to 39 parts of poly (vinyl chloride co-isobutyl vinyl ether), 3 to 5 parts of vaseline, 22 to 26 parts of crystal silicon micro-powder, 4 to 6 parts of triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane, 1 to 2 parts of 4-hydroxybenzoic acid hydrazide, 3 to 4 parts of zinc pyrrolidone carboxylic acid, 2 to 3 parts of stannous octoate, 4 to 6 parts of glyceryl tristearate, 15 to 20 parts of calcined kaolin, 3 to 4 parts of lead maleate tribasic, 1 to 2 parts of alpha-phenylindole, 21 to 27 parts of a composite fire retardant, and 1.5 to 2.5 parts of an anti-oxidant 1520. The cable material produced by the preparation method provided by the invention is low in water absorption and superior in water resistance, further has excellent performance such as high intensity, excellent thermal stability, shock resistance, aging resistance, corrosion resistance, fatigue resistance, environment friendliness and flame retardance, and the like, and has a very wide application prospect.