The invention relates to a comprehensive extraction method of glycyrrhiza, belonging to the field of the processing and extraction of herbal medicines. In the prior art, glycyrrhiza polysaccharide, glycyrrhizic acid and glycyrrhiza flavonoid are extracted from glycyrrhiza in a signal component way, and other components are all considered as impurities which run off with waste water and waste resides during the processing; the conventional method enables useful resources to run off in a great quantity, which not only pollutes the environment, but also improves the product cost; and the invention discloses the comprehensive extraction method of the three products from the glycyrrhiza, comprising the following steps of: extracting the glycyrrhizic polysaccharide from an acidic water solution of citric acid, adding ammonia water in residual herbal residues, continuously extracting coarse glycyrrhizic acid from an alkalescent water solution, then adding sodium hydroxide in the herbal residues, and extracting the glycyrrhiza flavonoid from an alkaline solution. The invention has the advantages of resource saving, simplified method and low production cost and can further utilize the wastes.