The invention belongs to the field of aquatic product deep processing, and especially relates to an industrial extraction method of mussel polysaccharide. According to the method, frozen cooked dried mussels are taken as the raw materials, the preparation method comprises steps of raw material pretreatment, extraction, dreg removal, enzymatic hydrolysis, filtration, ethanol precipitation, dehydration, filtration, and drying, the finished product of mussel polysaccharide is white powder, the yield of polysaccharide is 7.9 to 12.4%, and the content of mussel polysaccharide is 82 to 92%. The provided method has the advantages that the technology is simple, green, and environment-friendly, the polysaccharide yield is high, the purity is high, the method is suitable for industrialized enlargement, the steps are simple, the operation is convenient, and the practicality is strong.