Mg-5Li-1Al magnesium alloy sheets processed by hot rolling were annealed at 150℃ and 300℃ for 30 min, respectively. The microstructure, mechanical properties, and texture of rolled and annealed Mg-5Li-1Al alloy sheet were investigated. The plastic deformation mechanism was also discussed. The results show that the annealed sheet possesses weak basal texture and homogenous recrystallized structure with grain size of ~ 15 μm. Increasing annealing temperature results in an increase in tensile elongation and a decrease in tensile strength and yield ratio, which are generally favored for the improvement of sheet formability. The rolled LA51 sheet after annealing at 300℃ exhibits improved mechanical properties due to Li addition and high annealing temperature.