Extraction method of [alpha]-linolenic acid

An embodiment of the invention discloses an extraction method of [alpha]-linolenic acid, wherein the method comprises following steps: (1) decocting Chinese prickly ash seed oil in alkaline water and performing salting-out to obtain a solid; (2) neutralizing the solid with an acid to obtain a mixed fatty acid; (3) performing a gradient cooling process and performing filtrating to remove waxes and parts of saturated fatty acids and monounsaturated fatty acids to obtain a further mixed fatty acid; (4) wrapping the further mixed fatty acid with urea and performing filtration and crystallization to remove the saturated fatty acids and the monounsaturated fatty acids to obtain a mixture composed of linoleic acid and the [alpha]-linolenic acid; and (5) finally performing a complex reaction with silver nitrate to obtain an [alpha]-linolenic acid mixture. The invention aims to provide the extraction method of the [alpha]-linolenic acid, wherein the method is high in production efficiency and recovery rate and is suitable for large-scale application.