The invention discloses an extraction purification method and a detection method for pyrrolo[1,2-a]pyrazine-1,4-dione,hexahydro-3-(phenylmethyl) in euphausia superb. The extraction purification method comprises: adding methanol to euphausia superba, carrying out reflux extraction, and filtering to obtain a filtrate; carrying out evaporation concentration on the filtrate to obtain a methanol extract; adding diethyl ether to the methanol extract, leaching, and filtering to obtain a diethyl ether liquid; evaporating the diethyl ether liquid to obtain a diethyl ether extract; adding a proper amount of diethyl ether to the diethyl ether extract, dissolving to obtain a diethyl ether extract liquid, adding a sulfuric acid aqueous solution, and carrying out stirring extraction to obtain an acid water layer; adding chloroform to the acid water layer, extracting, and carrying out standing liquid separation to obtain a chloroform layer A; adding a sodium hydroxide aqueous solution to the obtained chloroform layer A, extracting, and carrying out standing liquid separation to obtain an alkali water layer and a chloroform layer B; and evaporating the obtained chloroform layer B to remove the solvent so as to obtain Cyclo(Pro-Phe), wherein the obtained Cyclo(Pro-Phe) is analyzed and detected by using gas chromatography-mass spectrometry (GC-MS). According to the present invention, the euphausia superba is adopted as the raw material, the Cyclo(Pro-Phe) is firstly extracted and purified from the euphausia superba, and the detection is performed, such that the important significance is provided for the development of the euphausia superba.