The invention relates to a high-pressure rubber hose and a preparation method thereof. A filler specialized for a flame-retardant and high wear-resistant high-pressure rubber hose is prepared from the following raw materials by weight: 10-14 parts of carbon black, 4-7 parts of nano pottery clay, 8-12 parts of paraformaldehyde, 0.3-0.6 part of hydroxyethyl tridecanyl imidazoline, 5-8 parts of magnesium dihydrogen phosphate, 2-3 parts of aluminium triphosphate, 1-2 parts of polyether silicone oil, 3-5 parts of dibutyl ester, 1-1.5 parts of paraffin, 50-55 parts of fly ash, a proper amount of 4-6% hydrochloric acid, a proper amount of water and 15-20 parts of an auxiliary agent. By adding paraformaldehyde, the filler provided by the invention has an anti-bacterial effect; by adding carbon black and nano pottery clay, the filler has good reinforcing property, and strength and wear resistance of the hose are greatly increased; by adding magnesium dihydrogen phosphate and aluminium triphosphate, flame retardance of the hose can be improved; by using the fly ash, cost is reduced and the reinforcing property is good; and by using the auxiliary agent provided by the invention, dispersibility and reinforcing property of the filler are increased, the strength, impact toughness of the high-pressure rubber hose can be increased, and the high-pressure rubber hose is not liable to bubble or deform.