The invention relates to the technical field of food processing, and discloses a method for extracting collagen in a fish skin by low-dose irradiation. Main processes comprise the following steps of making the fish skin into fish-skin minced meat, soaking the fish-skin minced meat in a fishiness removing solution, then making the fish-skin minced meat into fish-skin material liquid, afterwards, adding glyceride hydrolase, a flavor enzyme and a compound catabolic enzyme into the fish-skin material liquid, putting an obtained mixture in a cobalt-60 irradiation field to carry out irradiation, making the irradiated liquid material into a concentrated solution through heating inactivation, filtration, discoloration and concentration, and subjecting the concentrated solution to spray drying to make the collagen. According to the method for extracting the collagen by the low-dose irradiation, which is provided by the invention, through applying the irradiation to the material liquid in enzymolysis and degreasing processes, the enzymolysis rate can be improved; the hydrolyzation time is decreased; the degreasing effect is intensified; the yield and the quality of the collagen are improved; moreover, a microorganism can be effectively killed; the corrosion and deterioration prevention effects of the collagen are promoted; the preservation capacity of the collagen is enhanced; further, the molecular chain of the collagen becomes short; the average molecular weight is 1,500 to 3,500 daltons; the collagen is more suitably absorbed by a human body.