The invention discloses a method for extracting collagen from crucian carp skin. The method comprises steps of preprocessing, washing, enzymatic extraction, salting out, dialysis and freeze drying. The method has the following beneficial effects: the method adopts simple preparation steps andrequires a small quantity of devices, accurate data is provided for each step of operation, the reproducibility is good, and the method is suitable for large-scale production; the collagen is prepared from the crucian carp skin, namely, the crucian carp processing leftover as a raw material, the cost is low, the rate of utilization of the crucian carp is increased, and added value of the crucian carp is increased; the prepared collagen is high in biological activity and can be applied to the fields of drugs, food, health care products, cosmetics and the like; the speed for extracting the collagen with an enzymatic hydrolysis method is high, non-helical telopeptide can be selectively removed by pepsin, so that collagen molecules can be dissolved out, the triple helix structure of the collagen is retained, and the biological activity of the collagen is maintained.