Provided are a glyceride oil composition derived from a fish oil and a preparation method thereof. The composition includes docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA) with a content of 45 to 95% by weight and eicosapentaenoic acid (EPA) with a content of 0.001 to 13% by weight among constituent fatty acids, and a saturated fatty acid having 16 to 18 carbon atoms, which is bonded at 1- and 3-positions, with a content of 0.001 to 5% by weight among constituent fatty acids, in which a weight ratio of docosahexaenoic acid (DHA)/docosapentaenoic acid (DPA) is 0.5 to 8 and a weight ratio of docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) is 3.5 to 15. The glyceride oil composition derived from fish oil has nutritional and physiological superiority due to containing a great amount of polyunsaturated fatty acids such as DHA and DPA in a form of glyceride, and can minimize disadvantages of EPA such as inhibition of ω-6 fatty acid metabolism by containing a low amount of EPA. The glyceride oil composition is excellent in digestion and absorption of polyunsaturated fatty acids into a human body by containing a low amount of saturated fatty acids at 1- and 3-positions and process characteristics such as an oxidation stability and water-dispersibility.