Cod liver oil and fish oil differ in their sources, main ingredients, and uses. The sources of cod liver oil and fish oil are different. Cod liver oil is fat oil extracted from the liver of fish, part of the solid fat is removed at about 0ā, and the concentration is adjusted with refined edible vegetable oil, and then appropriate amount of stabilizer is added to make it. Fish oil is the general name for all the oil substances in the body of multi-fat and non-toxic fish, including body oil, liver oil, brain oil and so on. The main components and uses of cod liver oil and fish oil are different. Cod liver oil does not contain unsaturated fatty acids, the main components of vitamin A and vitamin Dā, the main role is to promote the absorption of calcium and phosphorus, to prevent rickets. Children’s supplementation of cod liver oil can protect the eyes and promote bone development, but due to the high content of vitamin A and vitamin D, it is easy to lead to excessive intake, vitamin D toxicity and so on. Fish oil is mainly composed of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and other unsaturated fatty acids, which have the ability to reduce triglycerides, and are beneficial to patients with high blood pressure, heart disease and atherosclerosis. Although fish oil is good, excessive supplementation will increase the risk of bleeding and lower the body’s immunity. Cod liver oil and fish oil are recommended to be used under professional guidance.