Welded joints of Al-Li alloy welded by YAG laser are investigated through metalloscopy, micro-hardness and electron probe micro-analysis. The results showed that a suitable welded joint can be obtained under proper welding parameters. The thoroughly penetrated thickness does not exceed 0.7 mm for the single impulse welding and 1.4 mm for the double impulse welding. The weld is narrow and has a fine grain structure while the wideness of the heat affected zone is small. Moreover, a stress releasing treatment must be done as soon as possible after welding.