The invention discloses a biological 
preservative and a preparation method thereof. The biological 
preservative is prepared from, by weight, 20-40 parts of 
nisin, 2-8 parts of trhalose, 5-10 parts of 
chitosan, 10-20 parts of compound 
amino acid, 4-8 parts of garlic, 10-15 parts of fresh ginger, 2-6 parts of pepper, 1-5 parts of clove, 2-8 parts of cinnamon, 2-6 parts of 
nutmeg, 2-5 parts of anise and 3-8 parts of fennel. According to the biological 
preservative, the components are subjected to compatibility, the synergistic effect is achieved, 
complementation and synergism are achieved, the bacteriostasis range can be enlarged, the preservative effect is enhanced, and the good 
antibacterial effect is achieved for 
bacteria, molds and 
yeast; meanwhile, garlic, fresh ginger, pepper, clove, cinnamon, 
nutmeg, anise and fennel contain a large number of natural active materials, the 
biological activity is achieved, amino acids are added jointly, the good health care functions such as 
appetite promotion and 
digestion aiding are achieved for body health, and the good popularization and application value is achieved.