NOVELTY - A lovastatin is prepared by mixing lovastatin crude solution and yeast fermentation medium, adding ethanol solution (3-7 ml) having a volume concentration of 45-85% to the mixture (1 g), reflux heating at 40-60 degrees C for 2-10 hours, collecting reflux extraction liquid and unloading lovastatin monascus; and collecting reflux extract having a molecular weight cutoff of 6000-30000 Da, subjecting to ultra-filtration at a pressure of 0.05-0.2 MPa, adding ethanol (45-85 vol.%) to the filtrate, mixing, and subjecting to ultra-filtration separation at 0.05-0.2 MPa to obtain lovastatin refined liquid.    USE - Method of preparing a lovastatin for preparing medicine for treating hypercholesterolemia or coronary heart disease.    ADVANTAGE - The method is simple and low cost, prepares product having a purity of more than 95%, is environment-friendly, and has high reliability and high utilization ratio of raw materials.    DETAILED DESCRIPTION - A lovastatin is prepared by:    (A) mixing lovastatin crude solution and yeast fermentation medium, adding ethanol solution (3-7 ml) having a volume concentration of 45-85% to the mixture (1 g), reflux heating at 40-60 degrees C for 2-10 hours, collecting reflux extraction liquid and unloading lovastatin monascus;    (B) collecting reflux extract having a molecular weight cutoff of 6000-30000 Da, subjecting to ultra-filtration at a pressure of 0.05-0.2 MPa, adding ethanol (45-85 vol.%) to the filtrate, mixing, and subjecting to ultra-filtration separation at 0.05-0.2 MPa to obtain lovastatin refined liquid;    (C) transporting the refined liquid to HZ802 or NAK9 or XDA16HP macroporous absorption resin column, eluting with distilled water, eluting with ethanol (45-75 vol.%), and collecting eluate; and    (D) heating the collected eluate at 50-90 degrees C and pressure of 0.05-0.09 MPa, decompressing and evaporating, freeze-drying the obtained product at - 30 to 10 degrees C for 6-10 hours, and drying at 50-60 degrees C and pressure of 40-60 Pa for 24-48 hours to obtain powder having a purity of 90-95%.