Abstract: The large electron beam welding machine with high or low vacuum is special equipment,used to weld titaniun alloy fuel tank and wel- ding seam of gas bottle of the satellite。On the basis of the advantages of vacuum electron beam welding machine from domestic and abroad and the new structure plan of this equipment was successfully developed.This article mainly introduces the working principle、technique properties,design and calculation of vacuum system,structure features.installation and adjustment,results as well as developing prospect ete.