The invention discloses a beef soup and a preparation method thereof. According to the technical scheme, the preparation method comprises the following steps that beef is cut into blocks, ox bones arebroken, meat boiling materials are added, small fire is used for decocting, and the beef soup is obtained; the meat boiling materials are prepared from a turnip, a carrot, sagittaria sagittifolia, aginger, an onion, garlic, salt, lycium chinensis, cyanide, a long pepper, rhizoma nardostachyos, star anise, vanilla, nutmeg, lemon thyme, a freshener and an antioxidant. The turnip, the sagittaria sagittifolia and the carrot in the soup are alkaline foods, and can neutralize the acidic substances in the beef soup so that a body fluid can achieve dynamic balance, thereby improving the fatigue of ahuman body eating excessive meat; the lycium chinensis, the long pepper, the rhizoma nardostachyos, the star anise, the vanilla, the nutmeg and the lemon thyme in the meat boiling materials can not only enrich the taste of the beef soup and increase the nutrients of the beef soup, but also help to promote digestion, increase appetite and prolong the preservation life of the beef soup.