The invention discloses a method for extracting isobavachalcone from fresh angelica keiskei. The method comprises the following steps: taking fresh angelica keiskei, pulping, removing chlorophyll, removing tannin with whitewash, carrying out ester liquid-alkali liquid two-phase extraction to remove fat-soluble impurities, carrying out macroporous resin adsorption, washing with water to remove carbohydrate matters, carrying out alcohol-water gradient elution to obtain an isobavachalcone crude product, and finally carrying out secondary recrystallization to obtain an isobavachalcone fine product of which the purity is 75 percent or above. The method has the characteristics that the yield is high, the reaction time is short, the production process is pollution-free, and no side product is generated; the obtained product is simplex in composition, and high in purity, and has important application and academic values in the biological activity fields such as the antineoplastic field, the antidiabetic field, the anti-hyperlipidemia field, the hypotensive field, the antibacterial field and the anti-inflammatory field, particularly a key function in research of the pharmic structure-function relationship of chalcone.