The invention provides a drink composition containing L-carnitine, plant extracts and water. The plant extracts are selected from barley seedling, barley or fried barley, chrysanthemum, honeysuckle, arabian jasmine flower, tea flower, bamboo leaf flavonoid, eucommia ulmoides male flower, medlar, herba houttuyniae and the like; furthermore, the drink composition also contains inositol, taurine, lysine or lysinate, caffeine, nicotinamide, vitamin B6 and vitamin B12. The invention further provides a preparation method of the drink composition, as well as application of the drink composition in preparation of drinks for supplementing the L-carnitine by oral administration, and burning fat to reduce weight, removing grease and cleansing the palate, clearing away heat and toxic materials, refreshing and relieving summer-heat, refreshing, resisting fatigue, improving appetite and promoting digestion, protecting cardio-cerebral vessels, regulating immunity, resisting fatigue and oxidation, protecting liver and treating fatty liver. According to the novel functional drink containing L-carnitine nutrition and the plant extracts, provided by the invention, the plant extracts and the L-carnitine are matched to realize cooperative nutrient and health functions.