A lighting device includes an optical lens, a scattering layer mounted on an outer surface of the optical lens, and a lighting module mounted on the optical lens and emitting a plurality light beams which are reflected and/or refracted by the optical lens and are reflected and/or refracted by the scattering layer. Thus, the light beams of the lighting module are initially reflected and/or refracted by the optical lens and are then reflected and/or refracted by the scattering layer so that the light beams of the lighting module are distributed in a two-stage manner by the optical lens and the scattering layer and are scattered and diverged in different angles and directions evenly and smoothly so as to provide a fully developed lighting effect, thereby enhancing the lighting efficiency of the lighting device.