Disclosed are azetidinone compounds and medical use thereof are provided by the present invention. More particularly, azetidinone compounds, shown as formula (I), wherein R1, R2, R3, R4, R5, R6 are defined in description, and preparation methods thereof are provided by the present invention. The compounds of the present invention can reduce the levels of total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) in plasma, and can be used as medicaments for reducing cholesterol in blood. Therefore the compounds of the present invention can be used to treat or prevent diseases of atherosclerosis, cacergasia of blood vessel, cardiac failure, coronary artery disease, angiocardiopathy, myocardial, angina, hyperlipoidemia and hypercholesteremia and the like. Preparation method of compounds of formula (I) and intermediate compounds are also provided by the present invention
