A gas discharge lamp includes a lamp tube, two electrodes and an electron emitter. The lamp tube has a hermetic discharge chamber filled with a rare gas and two sealing neck portions. Each of the sealing neck portions has a metallic foil disposed therein. Each of the two electrodes includes an emitting part and a connecting part. The connecting part is connected to a metallic wire via the metallic foil. The metallic wire extends out of the sealing neck portion to form a circuit contact. The electron emitter is made of a conductive material and electrically connected to one of the electrodes. A portion of the electron emitter disposed in the hermetic discharge chamber, and a diameter of an end of the electron emitter in the hermetic discharge chamber is less than an outer diameter of the connecting part.