The invention relates to a solid tire with high flexibility and a preparation method thereof. According to the technical scheme, the solid tire comprises a main material and an auxiliary material, the main material comprises natural rubber, and the auxiliary material comprises an accelerant, an antioxidant, zinc oxide, sulfur, a foaming agent, a coupling agent, a brightening agent, an anti-fatigue agent, stearic acid, coumarone resin, carbon black and an anti-wear agent. The solid tire with high flexibility and the preparation method have the beneficial effects that the accelerant ZS, the accelerant CZ and the accelerant DM are added according to a proper proportion, so that the tire has good elasticity and toughness and is environment-friendly, and the heat conduction performance of the tire is greatly improved by adding the zinc oxide into the natural rubber according to a proper proportion; the tire burst probability is reduced in the tire using process; a proper proportion of sulfur is added, so that the vulcanization performance is improved; the anti-fatigue agent and the tear-resistant resin are added according to a proper ratio, so that the tire is good in aging resistance, low in rolling resistance and stable in performance.