The present invention relates to a composition for treating keratin fibers, preferably hair, comprising: (a) at least one silicone oil in an amount of 20% by weight or more relative to the total weight of the composition; (b) water; and (c) at least one polyol in an amount of 10% by weight or more relative to the total weight of the composition, wherein the ratio of the amount of the (b) water/the amount of the (c) polyol is 3 or less. The composition according to the present invention can also provide keratin fibers such as hair with improved cosmetic effects such as smoothness (e.g., smooth combing even if the keratin fibers are wet, and smooth feeling to touch when the keratin fibers are dry), ease of running fingers through the keratin fibers even if the keratin fibers are wet, moist feeling even if the keratin fibers are dry, less stickiness (or less greasy) on hair when the keratin fibers are dry, and volume down control (therefore, it can be easy to style the shape of keratin fibers, due to anti-frizz properties of the composition according to the present invention).