Abstract: Through literature tracing, the key issues such as the historical origin, drug composition, base, preparation, dosage, decoction, and main treatment of Daotan Decoction were analyzed to provide literature support for the development and clinical application of the classic formula. After analysis and verification, Daotan Decoction derives from Wu Yankui's Circulated Applicable Prescriptions, which is composed of five medicines: Pinellia, Arisaema, Fructus Aurantii Immaturus, Tangerine peel, and Red Poria. Except for Red Poria, the bases of the other drugs follow the 2020 edition of Chinese Pharmacopoeia, among which Red Poria and Tangerine peel are used in the raw form, Pinellia is alum processed Pinellia, Fructus Aurantii Immaturus is Bran Fried Fructus Aurantii Immaturus, and Arisaema is prepared Arisaema. The dosage is suggested to be 6.00 g of Pinellia, 1.50 g of Arisaema, 1.50 g of Fructus Aurantii Immaturus, 1.50 g of Tangerine peel, and 1.50 g of Red Poria. When decocting Daotan Decoction, the drugs must be ground into pieces, sieved through No. 1 sieve, added with 10 g ginger and 600 mL of water, decocted to 300 mL, filtered to remove the residue, and taken after meals. This formula dries dampness, dispels phlegm, moves qi and relieves depression, and is mainly used for treating phlegm-drinking obstruction caused by phlegm-syncope, chest and diaphragm congestion, lateral thorax and rib distension and fullness, headache and vomiting, wheezing and coughing, sticky and thick snot and spittle, eating less and being dull, and pain in the joints and other phlegm manifestations.