In this study, the properties of egg yolk oil (EYO) were investigated. Water extraction, dialysis, and ultrafiltration were used to extract and purify EYO, and microscopy, spectrophotometry, and chromatography were used to identify carbon dots (CDs) present in EYO (EYO CDs). Morphology analyses demonstrated that CDs were almost spherical, with an average size of <10 nm, a lattice spacing of 0.267 nm, and a composition of mainly C, O, and Fe. The solution showed bright blue fluorescence at 365 nm. Tail haemorrhaging and liver haemorrhaging experiments showed that CD-treated mice had significantly shorter bleeding times than did control mice. Coagulation assays suggested that EYO CDs stimulate the intrinsic blood coagulation system and activate the fibrinogen system. Thus, EYO CDs possess the ability to activate haemostasis, which may lead to further investigations of this ingredient of traditional Chinese medicine.