The invention relates to a light source which comprises a conductive cathode, an anode layer which is distant with the conductive cathode to form a vacuum inner space, a fluorescent layer on the surface of said anode layer to emit visible lift when impacted by the electrons, a insulation layer inside said inner space and near the conductive cathode; and several electron emitters arranged at the surface of said insulation layer. Wherein, each said electron emitter comprises a cylinder and a taper sharp, while the cylinder and the insulation layer are made from similar diamond carbon material and the taper sharp is made from niobium metal. The invention has stable electron emitter, which can bear high electric field to improve the brightness and intension.