Abstract: Carbon quantum dots (CQDs), as a novel kind of zero-dimensional carbon-based nanomaterials, has excellent photoluminescence performance, biocompatibility, biodegradability, and is easy to be modified. In recent years, research on the preparation of CQDs using natural biomass raw materials as synthetic precursors had received widespread attention. This article used delimed cattlehide waste dandruff as raw material and achieved its functional modification by adding citric acid, sodium alginate, and itaconic acid, respectively. Four types of dandruff-based CQDs were synthesized using the one-pot hydrothermal method, and the application of these CQDs as masking agents in the tanning process was preliminarily explored. Results indicated that the synthesized CQDs could emit blue fluorescence under 365 nm ultraviolet light irradiation and displayed a spherical morphology and good dispersion and stability. They also exhibited good masking effect in chromium-free metal tanning systems.