The antioxidant activity of walnut oil was assessed by 1,1-diphenyl-2-picrylhydrazyl( DPPH) radical scavenging capacity,2,2-azinobis( ABTS) radical scavenging capacity and β-carotene bleaching test. Results of these studies demonstrated that walnut oil possessed antioxidant activities and a significant correlation( P < 0. 05) was found between these three methods and Rancimat methods assays. The content of total tocopherols,total phenolics,flavonoids,carotene,phospholipids,conjugated diene value and total carbonyl compounds were measured,and a good correlation obtained between them and OSI( P < 0. 01). Also,the five antioxidant composition( tocopherols,phenolics,flavonoids,carotene and phospholipids) contribution to the production of hydroperoxides were 40. 22 %,1. 94 %,19. 14 %,37. 92 % and 0. 79 %,respectively. The order of antioxidation activity of first level was tocopherols > β- carotene > flavonoids > phenolics > phospholipids; the order to inhibit second level oxidation was phenolics > tocopherols > flavonoids > phospholipids > β- carotene