The invention discloses a fattening pig premix additive for improving meat quality and a preparation method thereof, belonging to the field of feed additives. The feed consists of 30-90 parts of Gracilaria genus 30-90 parts, 30-90 parts of Haiyingcai, 50-80 parts of Ulva kongii, 40-100 parts of hawthorn, 40-120 parts of astragalus, 40-120 parts of serine, and 2000 parts by weight of the feed. Composed of 40-120 parts of glycine, 50-110 parts of leucine, 50-110 parts of isoleucine, 100-300 parts of soybean oil, 200-400 parts of linseed oil and a carrier. The premix additive only needs to be added in a small amount to the feed, which can effectively improve pork meat color, drip loss, tenderness, intramuscular fat content and muscle fiber type composition, and improve pork flavor, taste and nutritional value; the raw material source of the premix additive It is safe, has no side effects, and has no pollution to the environment.