Preservative and preparation method thereof

The invention relates to a preservative and a preparation method thereof. The preservative comprises the following components in parts by weight: 20-30 parts of liquorice, 10-15 parts of gingko leaves, 6-8 parts of fructus forsythia leaves, 5-8 parts of semen cassia, 2-3 parts of Chinese lobelia, 0.5-1 part of pepper, 0.2-0.8 part of pine needles, 1-3 parts of salt and 1-3 parts of chitosan. The preservative provided by the invention can be widely applied to preservation of foods such as drinks, fruit wine, liquid seasonings and the like, is good in preservative effect, is natural and non-toxic, overcomes the defect that a conventional preservative can do harm to human bodies, and has the effects of safety, non-toxicity, anti-bacteria and health.