The invention provides a heat-cured high-intensity flaky adhesive for an automobile and a preparation method thereof. The heat-cured high-intensity flaky adhesive for the automobile comprises three layers, wherein the upper layer is made of glass fiber cloth, the middle layer is made of a high-intensity adhesive, and the bottom layer is made of barrier paper. The high-intensity adhesive is prepared from synthetic rubber, a plasticizer, epoxy resin, thermoplastic resin, tackifying resin, a curing agent, a vulcanizing agent, an accelerating agent, an anti-aging agent and calcium carbonate. Due to the adoption of the flaky adhesive, the rigidity of a metal sheet can be increased greatly in the automobile manufacturing process, the running noise of the automobile can be reduced, and the comfort and the safety of the automobile are ensured. The heat-cured high-intensity flaky adhesive has high adhesion to an oil surface metal material, can be operated manually and directly in the construction process, is non-sticky, nontoxic and tasteless, has high manufacturability, is prevented from moving, and is convenient to use. The flaky adhesive can be cut according to different requirements onpositions, sizes and shapes and can be stored for over 3 months at the temperature of 25 DEG C.