Method for extracting alkannin from alkanet

The invention discloses a method for extracting alkannin from alkanet, which is characterized in that the alkanet is mixed with an aqueous solution containing alcohol in accordance with a certain ratio of material to liquid and put into a pulp refiner for homogenate extraction. Solid-liquid separation is carried out to a mixture obtained after the homogenate to obtain an extracting solution. Solid contents are then mixed with the aqueous solution containing alcohol according to a certain ratio of material to liquid and put into the pulp refiner for the homogenate extraction to obtain an extracting solution. The extracting solutions are merged and then decompression condensed to obtain a crude product of alkannin. The operation technology is mainly characterized by smooth process, simple operation, extraction at room temperature for avoidance of the degradation of alkannin, recyclable reagents used, low energy consumption, low production costs and high yield.