The invention provides a cerebrolysin hydrolysate injection and a preparation method thereof. The preparation method comprises the following steps: taking pig brain, removing impurities, and adding purified water for homogenizing; hydrolyzing homogenate through pepsin and pancreatin, and collecting a clear liquid; regulating the pH of the clear liquid to be 1.7-3, heating to 100-110 DEG C, insulating for 15-45min, then regulating pH to 8.0-9.0; conducting ultrafiltration through a 8-10kd membrane, and collecting filtrate; conducting column chromatography to the filtrate, collecting an eluent, regulating ph to 8.0-9.0, concentrating through an anion-exchange membrane, filtering through a 0.2mu m membrane to obtain a stock liquid; and freezing the stock liquid, then defreezing, adding an antioxidant, regulating the pH to be 6.9-7.5, and filtering respectively through a 8-10kd membrane and a 0.2mu m membrane. The polypeptide in the obtained cerebrolysin hydrolysate injection is similar to that of a control drug being more than or equal to 0.90, and the obtained cerebrolysin hydrolysate injection contains 16 amino acids, the nitrogen amount of total amino acids accounts for more than or equal to 85% of total nitrogen content, additional amino acids are not required, and the amino acids can be prepared completely by means of pig brain, thus being stable and safe.