The invention discloses a hydroxytyrosol-containing blood fat-reducing composition which is characterized by being prepared from hydroxytyrosol, hyaluronic acid, arginine and citrulline according to a certain ratio. The composition can increase the content of high-density lipoprotein cholesterol in blood and reduce the content of low-density lipoprotein cholesterol. The invention further provides application of the hydroxytyrosol composition in preparation of a medicine and a health product which have blood fat reducing and oxidization resisting functions, and application of the hydroxytyrosol composition in preparation of a medicine and a health product which can assist in preventing and treating cardiovascular and cerebrovascular diseases.