Abstract: L-carnitine is an essential nutrient which promotes the conversion of fat into energy in animals. It has the functions of regulating lipid metabolism, improving antioxidant and immune capabilities, etc., and plays an important role in human health and disease prevention. Based on the outline of the physiological functions of L-carnitine, this article systematically reviews the content of L-carnitine and its determination methods to provide the basic theoretical basis for the correct understanding of L-carnitine and the scientific utilization of L-carnitine resources in food. It also provides reference data for the acquisition of a simple, rapid, accurate and specific L-carnitine determination method and its application in practice.