Weight reduction is very important to aircraft. Laser welding technology is beneficial to reduce the weight of aircraft structure. However, due to the unclear laser welding properties of Al-Li alloy, the research on laser welding of Al-Li alloy is necessary. In current study, the temperature field, stress field and deformation of laser welding are simulated. The optimal welding parameters are obtained by simulation, which are used to weld the real Al-Li alloy sheet. Besides, the microstructure and mechanical property of welded joints are analyzed. It is found that the simulated optimal welding parameters are suitable for welding real Al-Li alloy sheet. And the simulation results are consistent with the experimental results.