The present invention relates to a coating composition for a film with low refractive index and a film prepared therefrom, and more precisely, a coating composition with low refractive index which contains dispersed porous organic/inorganic hybrid nano-particles or a colloid containing the dispersed nano-particles, a photocurable compound having unsaturated functional groups, photoinitiator or photosensitizer, or an organic siloxane thermosetting compound, and a solvent and a film prepared therefrom. According to the present invention, porous particles have been formed by using a structural regulator in a silane compound at a specific size, in order to be fitted for a film with low refractive index, and then the structural regulator has been eliminated by a simple process before forming the film, resulting in preparation of a film with extremely low refractive index at a low temperature of up to 120° C. which will be applied as a film with low refractive index or a film with low reflection for various uses including displays.