Abstract: Objetive: Culturing liquid hyphae with Hericium erinaceus pure strain. The medium was optimized to increase the content of Hericium erinaceus mycelium phenolic extracts. The composition of Hericium erinaceus mycelium phenolic extracts was analyzed, and the effects of phenolic extracts from Hericium erinaceus mycelium on lactic acid bacteria were also studied. Methods: Orthogonal design was used to study the effect on the total phenol content in liquid mycelium, and HPD-826 macroporous adsorption resin was used to purify it, and then HPLC-MS was used to determine its composition. Finally, adding the purified product to the lactic acid bacteria culture mediumm, and detected the effect on the number of viable lactic acid bacteria and its acid-production ability. Results: When the carbon source potato was 14%, nitrogen source peptone was 2% and inorganic salt MgSO₄ was 0.3%, the total phenol content of Hericium erinaceus mycelium reached 0.783 mg/g. Sixteen monomeric phenols were identified from the phenolic extract of Hericium erinaceus mycelium, accounting for 88.27%. The main monomeric phenols were gallic acid-O-glucoside, p-coumaric acid-O-gallic acid glucoside, ferulic acid, catechin benzyl sulfide, gallic acid and caffeic acid. Adding phenol extraction solution from Hericium erinaceus mycelium to MRS medium of Lactobacilluscasei, Lactobacillus acidophilus and Streptococcus intestinalis could increase the number of viable bacteria of three kinds of lactic acid bacteria. Conclusion: Phenolic extract from Hericium erinaceus mycelium can promote the growth of lactic acid bacteria and provide new resource raw materials for functional food.