The sugar-free red tangerine peel oral liquid for treating productive cough is prepared with red tangerine peel, sessile stemona root, almond, white swallowwort, tuckahoe and other Chinese medicinal materials. It is used to treat cough, asthma with abundant phlegm, cold, bronchitis and laryngopharyngitis. The oral liquid includes also supplementary material maltitol and corrective, which is selected from proteoglycan, sweetener and stevioside and is preferably stevioside,.