The invention provides a method for extracting fructus cannabis oligopeptide from a fructus cannabis cake. The method comprises the following steps: collecting the fructus cannabis cake with the oil content of lower than 1%, adding water, regulating the pH value to 9.0, adding sodium metabisulfite, carrying out solid-liquid separation, and collecting the liquid phase; adding a HCl solution into the liquid phase, regulating the pH value to 3.8-4.3, standing, carrying out secondary solid-liquid separation, and collecting the precipitate; adding water, heating to 40-55 DEG C, regulating the pH value to 7.0-9.0, adding a compound protease, carrying out enzymolysis for 3-6 hours, carrying out centrifugal filtration, and collecting the clear solution which is the fructus cannabis oligopeptide solution; and carrying out electrodialysis, concentration and freeze-drying to obtain the fructus cannabis oligopeptide powder. The fructus cannabis cake subjected to press deoiling is used as the raw material, the isoelectric point principle is combined to precipitate the protein, and the compound protease enzymolysis and freeze-drying are performed to obtain the fructus cannabis oligopeptide. The whole process utilizes the pure physical technique, and no chemical component is added; and thus, the method has the advantages of low cost and no environment pollution.