Aluminum lithium alloy has been used for aerospace structure because of its higher modulus and specific strength than conventional aluminum alloys. It also shows extraordinary resistance to high cycle fatifue, fatigue crack growth and monotonic as well as cyclic fracture at cryogenic emperatures. AA2195 is aluminum lithium alloy that is wedely used for space launch vehicle. By replacing AA2219 with AA2195 for propellant tank of launch vehicle the total dry weight can be saved by about 10%. Since the large tank requires the panel size which is not commercially available, welding is required. Since the lithium is a very reactive metal, friction stir welding is appropriate for this alloy. The current work is to compare results from electron beam welding and friction stir welding. the results provide valuable information for the optimal condition of joining AA2195 sheets for a large tankage structure of the space launcher.