The invention provides a preparation method of a carbon quantum dot fluorescent material. The method involves an ignitable plant leaf material, a combustion supporting substance, a solid fiber adsorption material layer, and a combustion furnace body. The method is characterized in that: the combustion furnace body is composed of an air inlet, a combustion chamber, and an exhaust gas outlet, and the solid fiber adsorption material layer is arranged at the exhaust gas outlet; when the plant leaf material combusts, the carbon quantum dot fluorescent material can be generated, is carried by gas and is adsorbed in the solid fiber adsorption material layer, when the solid fiber adsorption material is placed in water or a solvent, the carbon quantum dot fluorescent material can separate and precipitate out by itself. The method provided in the invention can directly use urban waste fallen leaves to prepare the carbon quantum dot fluorescent material and does not employ any chemical means to extract. The carbon quantum dot fluorescent material adsorbed in the solid fiber adsorption material layer is convenient for transportation and carrying, is pollution-free and nonhazardous, can be released by an aqueous solvent or static electricity, so that the carbon quantum dot fluorescent material can be taken out directly.