The invention relates to low-refractive optical fiber coating resin. The low-refractive optical fiber coating resin is prepared from, by weight, 30-65% of prepolymer A, 0-40% of prepolymer B, 2-8% of a photoinitiator, 20-40% of an active diluent and 0.5-2% of a silane coupling agent, and the sum of the weight percentages of all the components is 100%. The low-refractive optical fiber coating resin is high in adhesive power, optical fiber is not likely to be broken when bent, and the low-refractive optical fiber coating resin is low in refractive rate and can enlarge the digital transmission aperture of the optical fiber.