The invention discloses a pet food and a preparation method thereof. The pet food comprises a fish skin layer and a content matter, wherein the content matter is coated by the fish skin layer; the weight part ratio of the fish skin layer to the content matter is (2 to 3):(7 to 8); the content matter comprises livestock and poultry meat, salmon meat, corn starch, soy protein, sorbitol, potassium sorbate, glycerin, 95% edible alcohol, citric acid, dry flour, taurine, vitamin B3, vitamin C, green tea powder, fresh ginger powder, choline chloride, and phosphatidylserine. The pet food has the advantages that by combining the fish meat and the livestock and poultry meat, the meat content in the food is increased, the meat flavor is realized, the palatability is improved, the salt content of the whole food is decreased, the fishy smell is thinned, the functional food is favorable for the pet health, the resistance ability of the pet is enhanced, the bone is strong, the tear trace is reduced, and the wools are clean and bright; the phosphatidylserine is suitable for improving the brain nutrient, and promoting the brain development.