Various embodiments relate to a lens for omnidirectional illumination being rotationally symmetrical and including a light incident surface, a first refractive surface, a first reflective surface, a second refractive surface, and a third refractive surface. A first portion of light which passed through the light incident surface is refracted by the first refractive surface to produce first emergent light. A second portion of the light which passed through the light incident surface is reflected by the first reflective surface to the second refractive surface, and then is refracted by the second refractive surface to produce second emergent light. A third portion of the light which passed through the light incident surface is refracted by the third light refractive surface to produce third emergent light, the first emergent light, the second emergent light and the third emergent light jointly achieved omnidirectional illumination.