A method for preparing scutellarin aglycone with high purity, comprising the following steps: Step 1: 5,6,7,4'-tetramethoxy flavonoid of Formula was demethylated in a solvent by a demethylation reagent, to obtain a crude product of compound of Formula; Step 2: the crude product of compound of Formula was refluxed by heating with acetic anhydride for acylation when pyridine is used as the solvent and catalyst, in order to obtain the compound of Formula; Step 3: the compound of Formula was hydrolyzed by acid or alkali to obtain the compound of Formula for further purifying; Step 4: the compound of Formula for further purifying is refluxed with acetic acid using an aliphatic alcohol having 1 to 3 carbon atoms as the solvent, and after filtration, the press cake is washed using the corresponding aliphatic alcohol, and dried under reduced pressure, to obtain scutellarin aglycone with high purity; characterized in that (a) the solvent in step is selected from one or more of dichloromethane, trichloromethane, dimethyl sulfoxide, dimethyl formamide and pyridine; (b) the demethylation reagent in step is boron tribromide or anhydrous aluminium trichloride; (c) in step, the reaction temperature is in the range from 0 to 30°C when boron tribromide is used as the demethylation reagent, and in the range from 30 to 200°C when anhydrous aluminium trichloride is used as the demethylation reagent; (d) the temperature for the hydrolysis reaction in step is from -10°C to 40°C, and the reaction duration is from 1 to 20 hours; and (e) the reaction solvent in step is selected from one or more of acetone, water, methanol, ethanol, dichloromethane, dimethyl sulfoxide, tetrahydrofuran or dioxane. Step 1: 5,6,7,4'-tetramethoxy flavonoid of Formula was demethylated in a solvent by a demethylation reagent, to obtain a crude product of compound of Formula; Step 2: the crude product of compound of Formula was refluxed by heating with acetic anhydride for acylation when pyridine is used as the solvent and catalyst, in order to obtain the compound of Formula; Step 3: the compound of Formula was hydrolyzed by acid or alkali to obtain the compound of Formula for further purifying; Step 4: the compound of Formula for further purifying is refluxed with acetic acid using an aliphatic alcohol having 1 to 3 carbon atoms as the solvent, and after filtration, the press cake is washed using the corresponding aliphatic alcohol, and dried under reduced pressure, to obtain scutellarin aglycone with high purity; (a) the solvent in step is selected from one or more of dichloromethane, trichloromethane, dimethyl sulfoxide, dimethyl formamide and pyridine; (b) the demethylation reagent in step is boron tribromide or anhydrous aluminium trichloride; (c) in step, the reaction temperature is in the range from 0 to 30°C when boron tribromide is used as the demethylation reagent, and in the range from 30 to 200°C when anhydrous aluminium trichloride is used as the demethylation reagent; (d) the temperature for the hydrolysis reaction in step is from -10°C to 40°C, and the reaction duration is from 1 to 20 hours; and (e) the reaction solvent in step is selected from one or more of acetone, water, methanol, ethanol, dichloromethane, dimethyl sulfoxide, tetrahydrofuran or dioxane.