NOVELTY - 1-(2,4-Dihydroxy-phenyl)ethanone is reacted with benzoyl chloride, reflown for 6-12 hours in solvent and then subjected to rearrangement reaction, to obtain 3-hydroxy-4-(3-oxo-3-phenyl-propionyl)-phenyl benzoate. The product is cyclized and hydrolyzed using concentrated sulfuric acid, to obtain 6-hydroxy-3-phenyl-4H-naphthalen-1-one. The obtained product is dissolved in solvent, dimethyl sulfate is added to mixture at room temperature in presence of alkali and then methylated, to obtain 7-methoxyflavone.    USE - Synthesis of 7-methoxyflavone used for preparing veterinary drugs.    ADVANTAGE - The method efficiently and economically provides high yield of 7-methoxyflavone using simple process. The 7-methoxyflavone is environmentally-friendly.    DETAILED DESCRIPTION - Resorcinol is subjected to Friedel-Crafts reaction in acetic acid solution in presence of zinc chloride as catalyst to obtain 1-(2,4-dihydroxy-phenyl)-ethanone as intermediate (I). The molar ratio of resorcinol to acetic acid is 1:3-10. The intermediate (I) is reacted with benzoyl chloride at room temperature for more than 1 hour in presence of alkali and reflown for 6-12 hours in solvent and then subjected to rearrangement reaction, to obtain 3-hydroxy-4-(3-oxo-3-phenyl-propionyl)-phenyl benzoate as intermediate (II). The content of alkali is 3-6 times the content of benzoyl chloride. The content of solvent is 6-12 times the content of benzoyl chloride. The alkali is potassium carbonate, sodium hydroxide, potassium hydroxide or sodium hydride. The solvent is dimethylformamide or dimethyl sulfoxide. The molar ratio of intermediate (I) to benzoyl chloride is 1:2. The intermediate (II) is cyclized and hydrolyzed using concentrated sulfuric acid (more than 65%), to obtain 6-hydroxy-3-phenyl-4H-naphthalen-1-one as intermediate (III). The intermediate (III) is dissolved in solvent and dimethyl sulfate is added to mixture at room temperature in presence of alkali, and methylation reaction is carried out at 70-80 degrees C for more than 2 hours, to obtain 7-methoxyflavone. The molar ratio of intermediate (II) to dimethyl sulfate is 1:1-4.