The present invention provides a gas discharge tube. The gas discharge tube comprises at least two electrodes and an insulation tube body being in sealing connection with the gas discharge tube to form a discharge inner chamber; the gas discharge tube is provided with low-temperature sealing binding configured to seal the discharge inner chamber; and the low-temperature binding generates fusion at a special low temperature, and the discharge inner chamber generates air leakage. When the gas discharge tube is subjected to lightning stroke or surge overvoltage, the gas discharge tube is able to discharge lightning current or overvoltage, and the gas discharge tube is able to leak to cause open circuit so as to rapidly cut off the subsequent current when the gas discharge tube is subjected to a certain continuous power current or oversize power current and cause heating and temperature rising to fuse the low-temperature sealing binding.