The present invention discloses a composite fermented Chinese herbal medicine food preservative which is natural, high efficient, safe, non-toxic, etc. The food preservative selects safe and side effect free Chinese herbal medicines of coptis chinensis, houttuynia cordata, cloves, scutellaria baicalensis, rheum palmatum, phellodendron chinense barks, herba taching, pulsatilla chinensis, forsythia suspensa, dandelions, herba artemisiae scopariae, licorice, etc. Ultrasonic assisted extraction and microbial fermentation combined fermentation technology combines the antimicrobial active ingredients in the composite Chinese herbal medicines, Bacillus subtilis, and various antibacterial substances in the mannan, seaweed polysaccharides, etc. together. The food preservative product has a high leaching rate of active ingredients of the Chinese herbal medicines, has a broad antimicrobial range and a strong antibacterial ability, can effectively extend food preservation duration, and meet people's demand for healthy, safe, side effect free food preservatives.