PURPOSE: A method for preparing a mulberry branch extract is provided to produce a large amount of purified powder containing oxyresveratrol with anti-inflammatory and antiaging functions and to use trans-rasveratrol and moracin as a novel material for functional foods and cosmetic products. CONSTITUTION: A method for preparing a mulberry branch extract containing oxyresveratrol comprises the steps of: steaming mulberry branches for one hour and drying； adding 650 kg of a 75-95% ethanol solution to 100 kg of the dried mulberry branches and extracting by ultrasonic wave at 40-50°；C for 12 hours； concentrating the extract by reduced pressure； dissolving the concentrate in a 80% ethanol solution and incubating at room temperature； removing precipitate, adding normal-hexane, and fractioning； removing an upper layer oil and concentrating the lower layer； adding a 20% ethanol solution to the defatted ethanol extract of mulberry branches and suspending； treating the defatted ethanol extract with 10% pectinase and hydrolyzing at 30-40°；C for 12 hours to obtain a hydrolysate； fractioning the hydrolysate with an ethyl acetate solvent and concentrating the upper layer by reduced pressure； dissolving the concentrate using the 20% ethanol solution and adsorbing onto diaion HP-20 adsorption ion exchange column； washing the resultant with the 20% ethanol solution； and eluting the resultant with a 40% ethanol solution and concentrating. [Reference numerals] (AA) Dried mulberry branches(100kg)； (BB) CNCNF(650kg, 80% ethanol solution, ultrasonic extractor, 50°；C, 12 hours, twice)； (CC) Filter； (DD) Filtered liquid； (EE, LL) Concentrate by reduced pressure； (FF) Ethanol extract of the mulberry branches(10kg)； (GG) Re-dissolve(50kg, ethanol solution)； (HH) Incubate day and night； (II) Supernatant； (JJ) Defatting(100kg, normal-hexane)； (KK) Lower layer； (MM) Defatted ethanol extract of mulberry branches(8.5kg)； (NN) Suspend(50kg, 20% ethanol solution)； (OO) Enzyme treatment(4L,
