The summer slow-setting high-performance structural adhesive provided by the present invention and its preparation method include epoxy resin, silicon micropowder, nano calcium carbonate, chopped carbon fiber, modified graphene, polyamide, aromatic amine, and silane coupling agent. The present invention prepares A mixture by mixing and stirring epoxy resin, silicon micropowder, nanometer calcium carbonate, chopped carbon fiber, modified graphene and silane coupling agent, and prepares A mixture by mixing and stirring polyamide, aromatic amine, silicon micropowder and chopped carbon fiber To obtain the B mixture, take the A mixture and the B mixture with a mass ratio of 2:1 and stir them, and place them in a closed container to vacuumize and degas the air to prepare a high-performance structural adhesive. The high-performance structural adhesive has high bonding strength and weather resistance. Good durability, long application period in high temperature environment, no sagging, good thixotropy, high strength, certain rigidity and toughness, green environmental protection, convenient construction, etc., have good market prospects, suitable for promote.