An extraction method for costunolide comprises the following steps of choosing micheliamacclurel velamen as a raw material, drying and smashing; extracting 2 to 4 times with 95% of ethanol in reflux mode, combining extraction liquid and decompressing and concentrating to obtain coarse extractum; taking the dried coarse extractum to perform normal-pressure silica gel column chromatography, sequentially choosing petroleum ether - ethyl acetate of 10:1 and 5:1 as eluant to perform gradient elute, using thin-layer chromatography (TLC) to detect received liquid in all test tubes, adopting the elutant of 10:1 to elute a first spot material clean from a chromatography column, using the elutant of 5:1 to continue eluting, receiving a second spot material, confirming that no spot exists through TLC detection, finishing the column chromatography, combining the received liquid, and concentrating the received liquid to obtain white flaky crystal, namely the costunolide. The extraction method uses the micheliamacclurel velamen as the raw material to prepare monomer costunolide and is reasonable, convenient in operation, easy to obtain the raw material and capable of manufacturing costunolide monomers.