In the present study, highpurity linolenic acid products were obtained by twopass chromatography of linseed oil with ureasilica gel and cuprous chloridesilica gel. The results showed that linseed oil contained only oleic acid, linoleic acid and linolenic acid after ureasilica chromatography. A linolenic acid product with a purity higher than 90% was obtained after cuprous chloridesilica chromatography. Methyl linolenic acid was used as the standard for the external standard quantitative method. The total linolenic acid of the sample showed good linearity in the range of 0.045〖KG-*4〗~0.677 mg/mL. The regression equation was Y=782 59x-686 8(R2=0.999 9). This research will provide relevant theoretical basis and new ideas for the purification and industrial production of linolenic acid.