With the increasing demand for aircraft performance, structural weight reduction has become an important task in aerospace manufacturing industries. The Al-Li alloy exhibits many excellent performance including light weight, high strength, etc. These noteworthy advantages make it an ideal aerospace lightweight structural material with great development potential. At the same time, laser welding technology is considered as the most effective joining method for aluminum alloys. Nevertheless, the reliability of the welded structure is recognized as a challenge owing to the unique characteristics of the welded Al-Li alloy and the requirements of the civil aircraft industries. In this paper, the special micro-structure and defects in Al-Li alloy laser welded joint are introduced. The formation mechanism and inhibition measures of equiaxed grain along the fusion boundary (EQZ), welding pores, welding cracks and joint softening defects are analyzed.