NOVELTY - An arundoin is extracted from cogongrass by adding screened powder to kettle at 30-55 degrees C, pressure of 18-35 MPa and carbon dioxide flow speed of 15-30 kg/hour, adding ethyl acetate as entrainer based on material-to-liquid ratio of 1:0.5-1.5 (g/ml), extracting for 60-180 minutes, collecting cogongrass rhizome extracting liquid, recovering solvent and vacuum-drying into powder; and dispersing powder by water, passing through D101 macroporous resin column, eluting by 80-100% ethanol, collecting eluting solution and concentrating to obtain arundoin crude product.    USE - Method for the extraction of arundoin from cogongrass (claimed).    ADVANTAGE - The method has low energy consumption, no pollution, high preparation and high purity.    DETAILED DESCRIPTION - Extraction of arundoin from cogongrass comprises:    (A) taking cogongrass rhizome as raw material, cutting into 1 cm, placing in high-speed tissue breaking machine, keeping for 10 minutes at 10000 revolutions/minute, adding 85% chloroform solution based on a ratio of 1:10 (g/ml), adding 0.5% cellulase, performing enzymolysis for 30 minutes at 40 degrees C under ultrasonic power of 500 W, drying at low temperature, grinding and screening;    (B) adding screened powder to extraction kettle at 30-55 degrees C, extraction pressure of 18-35 MPa and carbon dioxide flow speed of 15-30 kg/hour, adding ethyl acetate as entrainer based on material-to-liquid ratio of 1:0.5-1.5 (g/ml), extracting for 60-180 minutes, collecting cogongrass rhizome extracting liquid, recovering solvent and vacuum-drying into powder;    (C) dispersing the vacuum-dried powder by water, passing through D101 macroporous resin column, eluting by 80-100% ethanol, collecting eluting solution and concentrating to obtain arundoin crude product; and    (D) separating and purifying the crude product by prepared or semi-prepared liquid phase chromatograph, taking methanol-water mixed solution as mobile phase, controlling methanol volume to 85-99% and flow speed to 5-100 ml/minute.