The n-3PUFA in the seal oil ethyl ester was enriched by urea adduction and molecular distillation. The physicochemical index， fatty acid composition and volatile substance in the seal oil during the enrichment were analyzed by physicochemical analysis， GC and HS-SPME-GC-MS. The results showed that the saponification value and iodine value were significantly improved by urea adduction and molecular distillation while had no significant effect on the acid value and peroxide value. The content of SFA was significantly decreased after urea adduction while n-3PUFA present the opposite tendency. There was a significant decrease in the content of MUFA. However， some long chain MUFA （C16：1，C18：1 and C20：1） still occupied larger percentage. The SFA and MUFA were separated effectively after molecular distillation and products with n-3PUFA content of 92.96% were obtained. There was no significant difference in the quantity of volatile substances between the material， urea adduction sample and molecular sample. The content of volatile substances in the urea adduction sample was significantly higher than the material and the material was significantly higher than that of the molecular distillation sample. The main volatile substances that contribute to the change were ethanol， 2-ethyl hexanol， fifteen carbon enol， nonanal， undecanal， 3，5-octadien-2-one， 2-nonanone， 2-heptanone.