Abstract:The composition and contents of the main fatty acids in the soybean oil and black soybean oil were analyzed by using gas chromatography，and a comparative analysis on the changes of the main fatty acids con－ tents and peroxide value in both oil during the storage were made by accelerated oxidation method. The results showed that four kinds of main fatty acids were included in soybean oil and black soybean oil，namely oleic acid， linoleic acid， palmitic acid and stearic acid， with the highest oleic acid content among them.The contents of un－ saturated fatty acids in soybean oil were higher than that in black soybean oil. During the storage， the contents of unsaturated fatty acids in these two edible oil were decreasing， the saturated fatty acids contents were substan－ tially invariant， and the peroxide value were decreasing， The peroxide value of soybean oil was slightly lower than the black soybean oil.