Sorbic acid is a new, safe, nontoxic and effective food preservative. It is unsaturated fatty acid. It can participate in normal metabolism and finally be oxidized to water and carbon dioxide, does not accumulate in the human body and has high safety. Its toxicity is only half of salt, 1/ 40 of sodium benzoate. Food grade sorbic acid has been approved of using in worldwide and successfully used in the food industry in many ways. It has obvious inhibition of molds, yeasts and aerobic bacteria, whose effect on inhibit the growth of bacteria is stronger than the effect on destroy bacteria. It combines with sulfhydryl group in microbial enzyme system to destroy the role of enzymes, so that achieve the purposes of bacteriostasis and antisepsis. It also can prevent from the growth and breeding of botox, staphylococcus and salmonella and other harmful microorganisms. Under acidic conditions (pH value less than 5-6), the effect of bacteriostasis is better, and the food composition has no any impact of preservative effect, so it effectively extends the storage time of food and keep the original flavor of food. However, there is no effect on anaerobic bacteria Bacillus and Lactobacillus acidophilus and other beneficial micro-organisms.