The invention discloses bone soup and a preparation method thereof. The bone soup comprises the following raw materials of cattle leg bones, chicken bones, dried scallions, fresh ginger, Chinese prickly ash, star aniseeds, bay leaves, radix angelicae, mature vinegar, garlic, green turnips, pepper powder, red jujubes, radix angelicae sinensis, dried orange peel, cortex eucommiae, galanga, Chinese wolfberry fruits, fructus momordicae, biond magnolia flowers, radix codonopsis, purple perilla, radix astragali, murraya paniculata, adenophora stricta roots, rhizoma kaempferiae, fennel fruits, cinnamon bark, fructus tsaoko, lysimachia capillipes, licorice roots and alpinia galanga seeds. The invention further provides a preparation method of the bone soup. The cattle leg bones and ecological free-range chickens are carefully selected and the bone soup is made. The bone soup is rich in meat taste, mellow in after taste, and rich in calcium and protein. The bone soup contains Chinese herbal medicine ingredients having the efficacy of strengthening the middle warmer, benefiting qi, invigorating the spleen, nourishing the lung, activating the spleen, promoting digestion, nourishing bodies, beautifying faces and the like, so that the effects of enhancing taste, enhancing freshness and enhancing fragrance can be achieved, and the nourishing efficacy of the bone soup is improved. The bone soup disclosed by the invention is prepared by performing stewing for about 8 hours by a slow-fire slow-decoction method, so that the decocted bone soup is clear and bright and high in the content of nutrient components.