As one of the important components in the power grid, gas-insulated switchgear requires high manufacturing precision and gas tightness. At present, the gas-insulated switchgear filling box is mainly welded by manual argon arc welding and manual assembly, which is difficult to ensure the welding quality of the filling box due to the problems of large welding deformation and poor airtightness. In view of the above difficulties, the automatic tooling fixture and laser welding process for gas-insulated switchgear gas tank laser welding were developed. Through experimental verification, the developed automatic tooling fixture can ensure the welding quality and deformation control of the inflatable box; compared with the TIG process, laser welding can reduce the welding deformation of the inflatable box, and the weld quality is excellent, stable and reliable; using the experimental design method of process optimization, the optimal process parameters of the laser gas-tight sealing welding for laser power of 1 800 W, the welding speed of 20 cm/min, shielding gas N₂, shielding gas flow 15-18 L/min, and finally, no leakage of gas in the inflatable box is found by helium mass spectrometry, and the sealing is good.