Complex experimental studies of the deformation and destruction of laser welds of modern aviation aluminum-lithium alloys doped with Mg and Cu have been carried out. The influence of mechanical and heat treatment of welded joints on the structure, strength and deformability of the weld, as well as the effect of temperature within the operating range (from -60 to +85C) on the destruction of the original and treated weld and its mechanical characteristics under static and low-cycle stretching, is investigated. The boundaries of the possible hardening of the seam by static pressing were determined for alloy 1420. It has been shown that, for alloys containing Cu, the pressing of a weld does not give results, and that with an increase in temperature, the non-uniformity of deformation of the untreated weld increases. This leads to a decrease in the ultimate strength and ultimate deformation of welded joints, and also increases their sensitivity to damage accumulation under low-cycle loading. The effect of quenching on the microstructure and mechanical properties of alloy B-1461 has been investigated. For it, the heat treatment mode of welded joints is determined, at which the ultimate load reaches 96%, and the ultimate deformation – 150% of the corresponding characteristics of the original alloy.