The invention discloses a cerebroprotein hydrolysate and a preparation method thereof. The extract is prepared by adopting the following method: (1) taking fresh and healthy pig brains, removing fat, homogenizing, then performing vacuum-pumping till 5-10Pa, keeping the pressure for 5-15 minutes, then introducing carbon dioxide until the pressure is 10-18MPa, and keeping the pressure for 20-25 minutes; (2) slowly adding the defatted brains with the saturated carbon dioxide into liquid carbon dioxide in the volume which is 5-8 times of the weight of the defatted brains, stirring for 0.5-2 hours after the end of adding, cooling down to minus 70-minus 80 DEG C, keeping for 2-4 hours, and then increasing the temperature to 40-50 DEG C within 5-10 minutes to gasify the carbon dioxide; (3) adding water for injection in the weight of 2-4 times of that of the frozen-thawed brains obtained in the step (2), uniformly stirring, further adding papain or pepsin which is equivalent to 0.5-1% of the weight of the frozen-thawed brains, and performing hydrolysis at the temperature of 30-40 DEG C for 3-4 hours to get an enzymatic hydrolysate; and (4) centrifugating the enzymatic hydrolysate, taking a supernatant liquid, performing activated carbon adsorption, performing decarbonization and filtering.