Provided are a method for extracting high-purity asarinin and use thereof, which belongs to the field of natural medicines. The method comprises: putting coarse asarum powder in a supercritical CO 2 extraction device; under the conditions that an extraction kettle has a pressure of 30-40 Mpa and a temperature of 45-70°C, separating kettles I and II have a pressure of 5-10 Mpa and a temperature of 30-50°C and the flow rate of CO 2 is 35-60 L/h, extracting for 60 to 240 minutes to obtain asarum total volatile oil; standing the asarum total volatile oil for 24-72 hours at a low temperature, and filtering under reduced pressure to obtain an asarinin coarse product; re-crystallizing the asarinin coarse product in absolute ethanol twice to obtain an asarinin pure product. In addition, it is found for the first time that asarinin has a good cough-relieving activity and thus can be used in preparing medicines for treating various types of coughs. Firstly disclosed is a brand-new preparation process for extracting asarinin by a supercritical CO 2 extraction method, and this method has the advantages of simple process, no solvent residue, high product purity, etc.