The invention provides a preparation method for a carbon quantum dot fluorescent material. The method comprises the following steps: through utilization of a plasma reinforced chemical vapor deposition technique, alternately depositing hydrogenated silicon carbide film (SiCX:H) and hydrogenated carbon nitride film (CNX:H) on a glass substrate by controlling deposition parameters, and then annealing in a vacuum furnace at 250-350 DEG C, thereby acquiring the fluorescent material embedded with the carbon quantum dot. Compared with the preparation method for coating or attaching the substrate, the preparation method provided by the invention has the advantages that the preparation process of efficient fluorescent carbon quantum dot is avoided, the carbon quantum dot and the multi-layer film structure are integrated with each other, hydrogen in the film is capable of effectively passivating the defects in the film and the fluorescence efficiency of the material is obviously increased. Thecarbon quantum dot fluorescent material prepared according to the invention has fluorescent performance stability and high illuminating efficiency and the preparation method is simple and environmentally friendly, so that the carbon quantum dot fluorescent material can be excellently applied to various semi-conductor illuminators.