The invention belongs to the technical field of functional materials, and particularly relates to a micro-nano coating material with low surface energy and a preparation method thereof. The preparation method comprises the following steps of mixing composite microspheres with micro sodium structure and hydrophobic nature, matrix resin with contact angle more than 90 degrees with coating film, solvent, powder, and additive, and adopting a co-mixing method, an in-situ emulsion polymerizing method, an in-situ solution polymerizing method, an in-situ concentration and polymerizing method, an in-situ addition and polymerizing method and the like, so as to prepare the coating material with micro-nano structure; performing spraying, brushing, roll coating, photo-etching, 3D (three-dimensional) printing, mechanical processing and the like, drying and curing at the temperature of 0 to 1000 DEG C, and coating the coating material with micro-nano structure onto different matrix surfaces, so as to obtain the micro-nano coating material with low surface energy and groove structure. The micro-nano coating material has the advantages that the preparation technology is simple, the coating hardness is high, the water-resistant property is good, the adhesion force to different matrix surfaces is strong, and the micro-nano coating material can be used for self-cleaning, resistance-reducing, denoising, anti-icing and other functional materials.