The invention provides a decorative material and a preparation method thereof and relates to the field of building materials. The decorative material comprises raw materials in parts by weight as follows: magnesium chloride, magnesium sulfate, magnesium oxide, expanded polystyrene, waste polyvinyl chloride foam plastic, glass fiber, talc powder, polyamide resin, phenolic resin, nano silicon carbide, a light stabilizer, a heat stabilizer, a compatilizer, a flame retardant and a plasticizer. The preparation method comprises the steps as follows: (1) weighing of the raw materials; (2) preparation of plastic particles; (3) stirring; (4) heating and extrusion forming. The problems that existing decorative materials are poor in fireproof performance, poor in energy-saving and environmental protection effect, low in strength and high in cost are solved.