The present invention provides an ultraviolet light oven for aligning liquid crystal molecules, comprising a plurality of ultraviolet light sources, each of the reflectors including a reflecting surface facing to the ultraviolet light source, wherein the reflector includes a first optical portion in the form of recess defined on the refracting surface. The present invention further provides an ultraviolet light oven for aligning liquid crystal molecules, and by providing a first optical portion on a reflecting surface of the reflector, and a second optical portion on the side surface of the reflector to as to properly reflect the light beam with is not directly projected toward the substrate and therefore increase the utilization of the ultraviolet light, the exposure and homogeneousness of the ultraviolet light. As a result, the exposing period is shortened, the working efficiency is increased.