The invention relates to a method for preparing high-purity pinolenic acid by a specific enzyme process, belonging to the field of food and health product processing. The method comprises the following steps: pine-seed oil Sn-1,3-specific lipase hydrolysis, Sn-2 glycerol monostearate separation, and hydrolysis of monoglycerol pinolenate. On the theoretical basis of using vegetable oil Sn-2 site as high unsaturated fatty acid, the Sn-1,3 site saturated/monounsaturated fatty acid is hydrolyzed, and the purification is carried out to obtain the pinolenic acid product with the content of greater than 80%. Compared with the traditional technique, the method provided by the invention has the advantage of no loss of pinolenic acid in the waste, reduces the operation steps, effectively lowers the production cost, is simple to operate, and can easily implement industrial production.