Abstract: Butt joints of 2.0 mm thick sheets of 2A97 aluminum-lithium alloy have been produced using laser autogenous welding method. The microstructure and properties of welded joints with different welding parameters (laser power and weld speed) were studied by optical microscope,scanning electron microscopy (SEM),microhardness tester and tension tester,respectively. The results show that the welded joint efficiency increase with the increasing of input power,the optimal input power is about 0.9-0.95 kJ/cm for 2A97 sheet with 2.0 mm thickness and the joint efficiency reach 0.8. The columnar grains zone (CGZ) is the weakness region of welded joint,the distribution of CGZ in fusion zone (FZ) increases with the decreasing of input power and accompanied with welding pore,which results in the dropping of welded joint efficiency.