Disclosed is an ultraviolet ray light source. The ultraviolet ray light source comprises a sealing cavity body and a luminous chip arranged in the sealing cavity body, wherein an output window is formed in the sealing cavity body; an electron emission apparatus, two electrodes, a reflective cup and a lens group are arranged in the sealing cavity body; the two electrodes are connected with the positive electrode and the negative electrode of a power supply respectively to form an accelerated electric field between the two electrodes; the electrodes are arranged in front of the outlet of the electro emission apparatus; the luminous chip is arranged in the reflective cup; and the lens group is arranged in front of the reflective cup. The electron emission apparatus generates electron beams; the electron beams pass through the electrodes to the luminous chip in a direction which is inclined from the horizontal direction so as to enable the luminous chip to generate ultraviolet light; and the ultraviolet light is reflected by the reflective cup and then passes through the lens group to be output through the output window. By adoption of the ultraviolet ray light source, the light beam shape and quality of the cathode ray ultraviolet light source can be adjusted.