The purpose of this study is to provide effective method of using separated liquid from hydrolyzate of ground mackerel by-product for making liquid fertilizer. Refined lipid from mackerel by-product was made and its fatty acid composition was analyzed. The sample was delivered from Samda Co. in Jeju, and oil was hydrolyzed and seperated but not refined. Crude lipid was degummed with 6% citric acid solution and phosphorous content (45mg/kg) was decreased to 5.8mg/kg. Acid value (18.03 mg KOH/g) was decreased to 1.19 mg KOH/g, peroxide value (30.25 meq/kg) was 3.18 meq/g and chromaticity (0.488) was 0.057 by adding 8% sodium hydroxide solution. Bleaching was conducted by adding 5% activated charcoal for 60℃ for 20 min under vacuum. After that, acid value was 0.17 mg KOH/g and peroxide value was 1.21 meq/kg, but chromaticity was not changed remarkably (0.062). In order to increase the amount of unsaturated fatty acids, crystalization was conducted at isolated and refined oil after processing. Refined and crystalizated lipid was analyzed by gas chromatography for quantitative and compositional analyses of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). After bleaching by activated charcoal, it was dissolved at 10 volume of hexane, and then stored at -70℃ for 12 hours. After the above process, the lipid was filtered with Buchner funnel at low temperature. Crude lipid of mono-unsaturated fatty acid composition was lower than viscera oil, but poly-unsaturated fatty acid composition had not much difference. Contents of DHA and EPA was increased by crystalization and total unsaturated fatty acid composition was 11% higher than before. Quantity of DHA and EPA also increased by crystalization. Total amount of EPA and DHA was 228.83mg/g. The result meant that it reached edible oil containing omega-3 fatty acid standard and available to using as omega-3 fatty acid product.