The invention discloses a common polypeptide in animal glue and application thereof in detection. The common polypeptide provided by the invention has a sequence of Gly-Ser-Ala-Gly-Pro-Hyp-Gly-Ala-Thr-Gly-Phe-Hyp-Gly-Ala-Ala-Gly-Arg. The polypeptide is common in the collagen sequence of donkeys, horses, cattle, pigs, sheep, turtles, tortoises, deer and other animals, and suffers a basically identical degree of production process destruction to that of collagen polypeptide components. Therefore, use of the common polypeptide as a reference substance or internal standard substance in mass spectrometry detection can offset different influences of the destructive degrees of different production processes, the content determination can be more accurate, and also whether other animal ingredients besides donkeys, horses, cattle, pigs, sheep, turtles, tortoises, deer are doped can be found timely.