Anglerfish skin-sourced collagen peptide with a liver damage repairing effect uses anglerfish skin as a raw material, and is prepared through pretreatment, enzymolysis with alkaline protease and ultrafiltration, wherein the pretreatment comprises the following specific steps: firstly washing the fish skin, soaking in distilled water with the temperature of 2-8 DEG C for 10-30min, then soaking in a6-12-fold sodium hydroxide solution with the concentration of 0.08-0.12mol / L by volume of for 20-24h, then washing by using clear water till a neutral state, draining the water, swelling for 9-15h byusing glacial acetic acid with the concentration of 0.08-0.12mol / L, and pulverizing to obtain anglerfish skin powder; the enzymolysis comprises the following specific steps: adding distilled water and the alkaline protease into the anglerfish skin powder, performing enzymolysis, deactivating enzyme after completion of the enzymolysis, centrifuging and taking a supernatant; the ultrafiltration comprises the following specific steps: performing ultrafiltration by using ultrafiltration membranes with the molecular weight of 8-10KDa, 5-8KDa, 3-5KDa, 1-3KDa and 1KDa below sequentially, and takinga part under the ultrafiltration membrane with the molecular weight of 1KDa below, and removing salt through nanofiltration, and then performing freeze drying. The anglerfish skin-sourced collagen peptide is applied to treatment of the nonalcoholic fatty liver disease.