To study the rancidity of dried file fish oil by Oxidation during the storage period, general properties of the oil and composition of its fatty acids were analysed qumtitatively with gas-chromatography. The results indicated that; 1) The dried file fish oil was involved in drying oil of heigh degree of unsaturation with IV 158., and consisted of higher-fatty acid with SV 190. 2) The composition of the fatty acids were composed of 18 fatty acids involving 6 unknown fatty acids, and polyunsaturated fatty acid with docosapentaenoic acid(20 weight%). 3) Changes of malonaldehyde content during the storage of dried file fish were about 5.0 mg/kg after 10day, 3.4 mg/kg after 40 days.