Abstract: Pulsed current heating technology was used to weld the 1420 Al-Li alloy.Samples welded with different conditions were compared.The best tensile strength of joints is 75% of the base metal.The influence of microstructure on properties of joints was analyzed.The welding process was analyzed by SEM images and micrograph pictures.Joined points occurred with a higher speed in the first step for micro-melting in the interface and a lower speed in the second step for atom diffusion.The grain size in the joints keeps steadily because of a shorter diffusion time.The fracture of the joints is a mixture of intergranular cracking and transgranular cracking.