The invention discloses a low-friction gelled acid and a preparation method thereof, and belongs to the field of acidification of oil wells. The low-friction gelled acid is prepared from: by weight, 0.2-0.5% of a gelling agent, 1-4% of a corrosion inhibitor, 0.1-1% of corrosion inhibition synergist, 1-2 % of an iron ion stabilizer, 1-2% of a cleanup additive, 15-23% of hydrochloric acid and the balance water, wherein the gelling agent is composed of a homopolymer of methacryloxyethyl trimethyl ammonium chloride and a chain extender, and the mass fraction of the chain extender in the gelling agent is 0.001-0.005%. According to the low-friction gelled acid provided in the embodiment of the invention, the molecular weight of the homopolymer in the gelling agent is effectively increased by adding the chain extender, so that the tackifying capability and resistance reduction performance of the gelling agent are improved; therefore, the friction of the gelled acid is reduced, the pressure required by a high-pressure pump truck during fracture acidizing is reduced, and energy and the cost of fracture acidizing are saved; meanwhile, by forming a chemical adsorption layer on the surface ofmetal through the cooperation of the corrosion inhibitor and the corrosion inhibition synergist, the corrosion to metal is slowed down.