The present invention relates to an oil composition containing a large amount of a diglyceride of conjugated linoleic acid (CLA), and more particularly to an oil composition with body weight control, anticancer, antioxidation and immune enhancement functions, which is based on a diglyceride of conjugated linoleic acid resulted from an enzymatic reaction between conjugated linoleic acid obtained from edible oil and glycerol. The inventive oil composition comprises 40-95% by weight of diglycerides, 5-60% by weight of triglycerides, 0.110% by weight of monoglycerides, and 0.02-10% by weight of residues, in which the ratio of conjugated linoleic acid (CLA) to fatty acids contained in the total glycerides is 5-98%. The use of the oil composition provides high-added-value foods, pharmaceutical compositions and foodstuff additives with effects of anticancer, immune enhancement, antioxidation, antichlorestol, growth promotion and the like.