NOVELTY - Essential oil and alpinetin are extracted from katsumadai seed by removing impurities of the seed, crushing, subjecting powder to supercritical carbon dioxide extraction to obtain essential oil component, collecting the extract, and filtering; mixing dreg and entrainer, subjecting mixture to supercritical carbon dioxide extraction, and collecting flavonoid component extract; and adding alcohol to the extract, filtering using ultrafiltration membrane, subjecting filtrate to polyamide resin column, eluting column with alcohol solution, and collecting fraction that is rich in alpinetin.    USE - Process of extracting an essential oil and alpinetin from katsumadai seed.    ADVANTAGE - The process simple process, produces less pollution, has low energy consumption and higher extraction ratio, and obtains product having high purity.    DETAILED DESCRIPTION - Essential oil and alpinetin are extracted from katsumadai seed by:    (A) removing impurities of the seed, crushing, subjecting powder to supercritical carbon dioxide extraction at 35-45 degrees C and pressure of 18-25 MPa for 1.3-5 hours with a carbon dioxide flow speed of 1.5-3 l/hour to obtain essential oil component, and collecting the extract in the separating kettle A controlled at 30-40 degrees C and pressure of 5.5-7.5 MPa and separating kettle B controlled at 30-45 degrees C and pressure of 5-6 MPa;    (B) mixing dreg and entrainer (0.1-0.2 times dreg quantity);    (C) subjecting mixture to supercritical carbon dioxide extraction at 55-75 degrees C and pressure of 30-45 MPa for 2-5 hours with a carbon dioxide flow speed of 1.5-3 l/hour;    (D) collecting flavonoid component extract in separating kettle C controlled at 40-45 degrees C and pressure of 7-10 MPa and separating kettle D controlled at 30-45 degrees C and pressure of 5-6.5 MPa;    (E) adding 70% alcohol to the extract, filtering using ultrafiltration membrane at 0.5-1 MPa, subjecting filtrate to polyamide resin column, eluting column with a75-90% alcohol solution (4-8 times column volume), and collecting fraction that is rich in alpinetin; and    (F) decompressing the alpinetin fraction to recover solvent, crystallizing, adding absolute methanol, reflux heating, cooling, crystallizing, filtering, crystallizing, and drying.