The invention relates to a sleep-improving composition and a preparation method thereof. The sleep-improving composition comprises, by weight, 5-50 parts of seed of wild jujube, 5-50 parts of fleeceflower stem, 5-40 parts of root of red-rooted salvia, 5-40 parts of root of thinleaf milkwort, and 5-30 parts of fruit of Chinese magnoliavine. The sleep-improving composition with good compatibility ofthe medicinal materials can nourish yin and blood and keep the heart in communication with the kidney so as to tranquilize mind by nourishing the heart. The sleep-improving composition is made by subjecting the materials to water extraction prior to alcohol precipitating and concentrating; the obtained sleep-improving composition may serve as a sleep-improving medicament or health-care product, having high safety and wide range of applicability, is convenient to take, has clear effect and is suitable for long-term administration. The sleep-improving composition provided herein is made from traditional Chinese medicinal materials, is significantly shorter than western medicine in half-life period, has low biotoxicity and can effectively avoid drug tolerance and addiction.