A light-diffusing LED lens adopting an asymmetric free-form surface expression is provided to improve the uniformity ratio of illumination of the target region by controlling the light from the LED serving as a light source. The light-diffusing LED lens adopting an asymmetric free-form surface expression exhibits light control and illumination efficiency suitable for highway environment conditions and characteristics of traffic lanes. Both the light incident surface and the light emitting surface of the light-diffusing LED lens are formed into an aspherical surface, in which an asymmetrical free-form surface is optimally utilized to enable the free-form surface to be freely modified and changed by adjusting the coefficients of the aspherical surface or the like. The light-diffusing LED lens enables a numerical design and a mathematical design by means of the free-form surface, and enables a fine control to be performed by numerical control to thus improve accuracy of light control.