2198-T851 Aluminum-Lithium alloy is a new high-strength material with low density, high specific strength, good corrosion resistance and well properties in low temperature condition. 2198-T851 with a thickness of 1.8 mm is welded with 2319 filler wire (Al-Cu) by using 6 kW fiber laser on butt welding. The effect of welding parameters on the weld formation and hot cracking are investigated, as well as testing the mechanical properties of the joint and analyzing of fracture morphology.The results indicate that a good joint with well weld formation and no hot cracks is obtained under the appropriate laser power, welding speed and wire feeding rate. The average tensile strength of joint reaches to 272 MPa and the extension rate of joint is 1.6%, the tensile fracture happens in the weld zone with ductile fracture characteristics.