The present disclosure discloses a 1-carboxy-2-hydroxy-3-iminopropane and an extraction method thereof, and belongs to the technical fields of food, health food and medicine. A method for extracting the 1-carboxy-2-hydroxy-3-iminopropane of the present disclosure includes the following steps: (1) adding a diaphragma juglandis fructus powder into an ethanol solution for extraction and filtration to obtain a supernatant, and conducting concentration on the supernatant under reduced pressure to obtain a walnut alcohol extract; (2) adding a filter residue of step (1) into water for extraction and filtration to obtain a supernatant, and conducting concentration on the supernatant under reduced pressure to obtain a walnut water extract; and (3) mixing the walnut alcohol extract and the water extract to obtain a diaphragma juglandis fructus mixed extract, sequentially conducting elution through an AB-8 type macroporous resin column, an MCI column and an ODS column, and conducting separation to obtain a precipitate, namely the 1-carboxy-2-hydroxy-3-iminopropane. In the present disclosure, the 1-carboxy-2-hydroxy-3-iminopropane in diaphragma juglandis fructus is found for the first time and has great sedation and hypnosis activity.