The composition and contents of the main fatty acids were analyzed by gas chromatography (GC) in the linseed oil. The changes of the main fatty acids and peroxide value in the linseed oil during the storage were analysed by ccelerated oxidation method. The results showed that five kinds of main fatty acids are included in linseed oil, namely linolenic acid, linoleic acid, oleic acid, palmitic acid and stearic acid, and 53.6% of them was linolenic acid. With the extension of storage time, the contents of every kind of unsaturated fatty acids in linseed oil decreased, showing a linear relevance to the degree of unsaturation. Moreover, the peroxide value was found decreased also, but the saturated fatty acids contents unchanged.